List of Backlinks is empty when both "Collapse results" and "Show only backlinks in the current page" are ON

[voltel]

Steps to reproduce

In the Sandbox vault

1. Go to Community plugins in Settings, install and enable the PDF++ plugin
2. Create a new Obsidian note "Test page.md"
3. While on the "Test page", drop any PDF file, e.g. "observations.pdf" onto the page in "Edit mode". (For example, sample PDF files can be downloaded from here). I downloaded this file which I renamed to "observations.pdf".
4. Open "observations.pdf" in a new Obsidian tab.
5. Select any text of the first page and right-click to choose e.g. "Copy link to selection with format Callout"
6. Return to the "Test page.md" and past the clipboard content. A new markup will appear:

> [!PDF|] [[observations.pdf#page=1&selection=10,0,14,20|observations, p.1]]
> You will need Adobe Acrobat Reader. You can install it for free here: get.adobe.com/reader

7. Return to the PDF viewer of "observations. pdf". In the side panel, find the backlinks panel and activate it
8. By default, the "Show only backlinks in the current page" option button is "ON". Ensure it stays "ON" (blue color of the icon).
9. By default, the "Collapse results" option button is "OFF" (gray color of the icon). Switch it "ON" (blue color of the icon).
10. Observe, that when both option buttons "Show only backlinks in the current page" and "Collapse results" are "ON" (blue color of the icons), the list of backlinks is empty (unexpected).

Expected behavior

A list of files with links to the PDF is expected, i.e.:

Linked mentions   2

> Test page     2

Actual behavior

A list of files with links to the PDF is empty, i.e.:

Linked mentions   0 in this page

Screen recordings or screenshots (sandbox vault)

Obsidian debug info

SYSTEM INFO:
Obsidian version: v1.5.11
Installer version: v1.4.13
Operating system: Windows 10 Home 10.0.19045
Login status: not logged in
Insider build toggle: off
Live preview: on
Base theme: adapt to system
Community theme: none
Snippets enabled: 0
Restricted mode: off
Plugins installed: 1
Plugins enabled: 1
1: PDF++ v0.39.0

RECOMMENDATIONS:
Community plugins: for bugs, please first try updating all your plugins to latest. If still not fixed, please try to make the issue happen in the Sandbox Vault or disable community plugins.

PDF++ debug info

{
    "settings": {
        "displayTextFormats": [
            {
                "name": "Title & page",
                "template": "{{file.basename}}, p.{{pageLabel}}"
            },
            {
                "name": "Page only",
                "template": "p.{{pageLabel}}"
            },
            {
                "name": "Text",
                "template": "{{text}}"
            }
        ],
        "defaultDisplayTextFormatIndex": 0,
        "syncDisplayTextFormat": true,
        "syncDefaultDisplayTextFormat": false,
        "copyCommands": [
            {
                "name": "Quote",
                "template": "> ({{linkWithDisplay}})\n> {{selection}}\n"
            },
            {
                "name": "Link only",
                "template": "{{linkWithDisplay}}"
            },
            {
                "name": "Embed",
                "template": "!{{link}}"
            },
            {
                "name": "Callout",
                "template": "> [!{{calloutType}}|{{color}}] {{linkWithDisplay}}\n> {{text}}\n"
            },
            {
                "name": "Quote in callout",
                "template": "> [!{{calloutType}}|{{color}}] {{linkWithDisplay}}\n> > {{text}}\n> \n> "
            }
        ],
        "useAnotherCopyTemplateWhenNoSelection": false,
        "copyTemplateWhenNoSelection": "{{linkToPageWithDisplay}}",
        "trimSelectionEmbed": false,
        "embedMargin": 50,
        "noSidebarInEmbed": true,
        "noSpreadModeInEmbed": true,
        "embedUnscrollable": false,
        "singleTabForSinglePDF": true,
        "highlightExistingTab": false,
        "existingTabHighlightOpacity": 0.5,
        "existingTabHighlightDuration": 0.75,
        "paneTypeForFirstPDFLeaf": "left",
        "openLinkNextToExistingPDFTab": true,
        "openPDFWithDefaultApp": false,
        "openPDFWithDefaultAppAndObsidian": true,
        "focusObsidianAfterOpenPDFWithDefaultApp": true,
        "syncWithDefaultApp": false,
        "dontActivateAfterOpenPDF": true,
        "dontActivateAfterOpenMD": true,
        "highlightDuration": 0.75,
        "noTextHighlightsInEmbed": false,
        "noAnnotationHighlightsInEmbed": true,
        "persistentTextHighlightsInEmbed": true,
        "persistentAnnotationHighlightsInEmbed": false,
        "highlightBacklinks": true,
        "selectionBacklinkVisualizeStyle": "highlight",
        "dblclickEmbedToOpenLink": true,
        "highlightBacklinksPane": true,
        "highlightOnHoverBacklinkPane": true,
        "backlinkHoverColor": "",
        "colors": {
            "Yellow": "#ffd000",
            "Red": "#ea5252",
            "Note": "#086ddd",
            "Important": "#bb61e5"
        },
        "defaultColor": "",
        "defaultColorPaletteItemIndex": 0,
        "syncColorPaletteItem": true,
        "syncDefaultColorPaletteItem": false,
        "colorPaletteInToolbar": true,
        "noColorButtonInColorPalette": true,
        "colorPaletteInEmbedToolbar": false,
        "showStatusInToolbar": true,
        "highlightColorSpecifiedOnly": false,
        "doubleClickHighlightToOpenBacklink": true,
        "hoverHighlightAction": "preview",
        "paneTypeForFirstMDLeaf": "right",
        "singleMDLeafInSidebar": true,
        "alwaysUseSidebar": true,
        "ignoreExistingMarkdownTabIn": [],
        "defaultColorPaletteActionIndex": 4,
        "syncColorPaletteAction": true,
        "syncDefaultColorPaletteAction": false,
        "proxyMDProperty": "PDF",
        "hoverPDFLinkToOpen": false,
        "ignoreHeightParamInPopoverPreview": true,
        "filterBacklinksByPageDefault": true,
        "showBacklinkToPage": true,
        "enableHoverPDFInternalLink": true,
        "recordPDFInternalLinkHistory": true,
        "alwaysRecordHistory": true,
        "renderMarkdownInStickyNote": true,
        "enablePDFEdit": false,
        "author": "",
        "writeHighlightToFileOpacity": 0.2,
        "defaultWriteFileToggle": false,
        "syncWriteFileToggle": true,
        "syncDefaultWriteFileToggle": false,
        "enableAnnotationDeletion": true,
        "warnEveryAnnotationDelete": false,
        "warnBacklinkedAnnotationDelete": true,
        "enableAnnotationContentEdit": true,
        "enableEditEncryptedPDF": false,
        "pdfLinkColor": "#04a802",
        "pdfLinkBorder": false,
        "replaceContextMenu": true,
        "executeBuiltinCommandForOutline": true,
        "executeBuiltinCommandForZoom": true,
        "executeFontSizeAdjusterCommand": true,
        "closeSidebarWithShowCommandIfExist": true,
        "autoHidePDFSidebar": false,
        "outlineDrag": true,
        "outlineContextMenu": true,
        "outlineLinkDisplayTextFormat": "{{file.basename}}, {{text}}",
        "outlineLinkCopyFormat": "{{linkWithDisplay}}",
        "recordHistoryOnOutlineClick": true,
        "popoverPreviewOnOutlineHover": true,
        "thumbnailDrag": true,
        "thumbnailContextMenu": true,
        "thumbnailLinkDisplayTextFormat": "{{file.basename}}, page {{pageLabel}}",
        "thumbnailLinkCopyFormat": "{{linkWithDisplay}}",
        "recordHistoryOnThumbnailClick": true,
        "popoverPreviewOnThumbnailHover": true,
        "annotationPopupDrag": true,
        "useCallout": true,
        "calloutType": "PDF",
        "calloutIcon": "highlighter",
        "highlightBacklinksInEmbed": false,
        "highlightBacklinksInHoverPopover": false,
        "highlightBacklinksInCanvas": true,
        "clickPDFInternalLinkWithModifierKey": true,
        "clickOutlineItemWithModifierKey": true,
        "clickThumbnailWithModifierKey": true,
        "focusEditorAfterAutoPaste": true,
        "respectCursorPositionWhenAutoPaste": true,
        "autoCopy": false,
        "autoFocus": false,
        "autoPaste": false,
        "autoFocusTarget": "last-active-and-open-then-last-paste",
        "autoPasteTarget": "last-active-and-open-then-last-paste",
        "openAutoFocusTargetIfNotOpened": true,
        "howToOpenAutoFocusTargetIfNotOpened": "right",
        "closeHoverEditorWhenLostFocus": true,
        "closeSidebarWhenLostFocus": true,
        "openAutoFocusTargetInEditingView": true,
        "executeCommandWhenTargetNotIdentified": true,
        "commandToExecuteWhenTargetNotIdentified": "switcher:open",
        "autoPasteTargetDialogTimeoutSec": 20,
        "autoCopyToggleRibbonIcon": true,
        "autoCopyIconName": "highlighter",
        "autoFocusToggleRibbonIcon": true,
        "autoFocusIconName": "zap",
        "autoPasteToggleRibbonIcon": true,
        "autoPasteIconName": "clipboard-paste",
        "viewSyncFollowPageNumber": true,
        "viewSyncPageDebounceInterval": 0.3,
        "openAfterExtractPages": true,
        "howToOpenExtractedPDF": "tab",
        "warnEveryPageDelete": false,
        "warnBacklinkedPageDelete": true,
        "extractPageInPlace": false,
        "askExtractPageInPlace": true,
        "pageLabelUpdateWhenInsertPage": "keep",
        "pageLabelUpdateWhenDeletePage": "keep",
        "pageLabelUpdateWhenExtractPage": "keep",
        "askPageLabelUpdateWhenInsertPage": true,
        "askPageLabelUpdateWhenDeletePage": true,
        "askPageLabelUpdateWhenExtractPage": true,
        "copyOutlineAsListFormat": "{{linkWithDisplay}}",
        "copyOutlineAsListDisplayTextFormat": "{{text}}",
        "copyOutlineAsHeadingsFormat": "{{text}}\n\n{{linkWithDisplay}}",
        "copyOutlineAsHeadingsDisplayTextFormat": "p.{{pageLabel}}",
        "copyOutlineAsHeadingsMinLevel": 2,
        "newFileNameFormat": "",
        "newFileTemplatePath": "",
        "newPDFLocation": "current",
        "newPDFFolderPath": "",
        "rectEmbedStaticImage": false,
        "rectImageFormat": "file",
        "rectImageExtension": "webp",
        "zoomToFitRect": false,
        "rectEmbedResolution": 100,
        "includeColorWhenCopyingRectLink": true,
        "backlinkIconSize": 50,
        "showBacklinkIconForSelection": false,
        "showBacklinkIconForAnnotation": false,
        "showBacklinkIconForOffset": true,
        "showBacklinkIconForRect": false,
        "showBoundingRectForBacklinkedAnnot": false,
        "hideReplyAnnotation": false,
        "showCopyLinkToSearchInContextMenu": true,
        "searchLinkHighlightAll": "true",
        "searchLinkCaseSensitive": "true",
        "searchLinkMatchDiacritics": "default",
        "searchLinkEntireWord": "false",
        "dontFitWidthWhenOpenPDFLink": true,
        "preserveCurrentLeftOffsetWhenOpenPDFLink": false,
        "defaultZoomValue": "page-width",
        "scrollModeOnLoad": 0,
        "spreadModeOnLoad": 0,
        "hoverableDropdownMenuInToolbar": true,
        "zoomLevelInputBoxInToolbar": true,
        "popoverPreviewOnExternalLinkHover": true,
        "actionOnCitationHover": "pdf-plus-bib-popover",
        "anystylePath": ""
    },
    "styleSettings": null,
    "styleSheet": ".pdf-plus-backlink-highlight-layer .pdf-plus-backlink:not(.hovered-highlight)[data-highlight-color=\"yellow\"],\n.pdf-embed[data-highlight-color=\"yellow\"] .textLayer .mod-focused {\n    --pdf-plus-color: #ffd000;\n    --pdf-plus-backlink-icon-color: #ffd000;\n    --pdf-plus-rect-color: #ffd000;\n}\n.pdf-plus-backlink-highlight-layer .pdf-plus-backlink:not(.hovered-highlight)[data-highlight-color=\"red\"],\n.pdf-embed[data-highlight-color=\"red\"] .textLayer .mod-focused {\n    --pdf-plus-color: #ea5252;\n    --pdf-plus-backlink-icon-color: #ea5252;\n    --pdf-plus-rect-color: #ea5252;\n}\n.pdf-plus-backlink-highlight-layer .pdf-plus-backlink:not(.hovered-highlight)[data-highlight-color=\"note\"],\n.pdf-embed[data-highlight-color=\"note\"] .textLayer .mod-focused {\n    --pdf-plus-color: #086ddd;\n    --pdf-plus-backlink-icon-color: #086ddd;\n    --pdf-plus-rect-color: #086ddd;\n}\n.pdf-plus-backlink-highlight-layer .pdf-plus-backlink:not(.hovered-highlight)[data-highlight-color=\"important\"],\n.pdf-embed[data-highlight-color=\"important\"] .textLayer .mod-focused {\n    --pdf-plus-color: #bb61e5;\n    --pdf-plus-backlink-icon-color: #bb61e5;\n    --pdf-plus-rect-color: #bb61e5;\n}\n.pdf-plus-backlink-highlight-layer .pdf-plus-backlink:not(.hovered-highlight) {\n    --pdf-plus-color: rgb(var(--text-highlight-bg-rgb));\n    --pdf-plus-backlink-icon-color: rgb(var(--text-highlight-bg-rgb));\n    --pdf-plus-rect-color: rgb(var(--text-highlight-bg-rgb));\n}\n.pdf-plus-backlink-highlight-layer .pdf-plus-backlink.hovered-highlight {\n\t--pdf-plus-color: green;\n\t--pdf-plus-backlink-icon-color: green;\n   --pdf-plus-rect-color: green;\n}\n.pdf-plus-color-palette-item[data-highlight-color=\"yellow\"] > .pdf-plus-color-palette-item-inner {\n    background-color: #ffd000;\n}\n.pdf-plus-color-palette-item[data-highlight-color=\"red\"] > .pdf-plus-color-palette-item-inner {\n    background-color: #ea5252;\n}\n.pdf-plus-color-palette-item[data-highlight-color=\"note\"] > .pdf-plus-color-palette-item-inner {\n    background-color: #086ddd;\n}\n.pdf-plus-color-palette-item[data-highlight-color=\"important\"] > .pdf-plus-color-palette-item-inner {\n    background-color: #bb61e5;\n}\n.pdf-plus-color-palette-item:not([data-highlight-color]) > .pdf-plus-color-palette-item-inner {\n    background-color: transparent;\n}\n.workspace-leaf.pdf-plus-link-opened.is-highlighted::before {\n\topacity: 0.5;\n}\nbody {\n    --pdf-plus-yellow-rgb: 255, 208, 0\n}\nbody {\n    --pdf-plus-red-rgb: 234, 82, 82\n}\nbody {\n    --pdf-plus-note-rgb: 8, 109, 221\n}\nbody {\n    --pdf-plus-important-rgb: 187, 97, 229\n}\nbody {\n    --pdf-plus-default-color-rgb: var(--text-highlight-bg-rgb)\n}\n.callout[data-callout=\"pdf\"][data-callout-metadata=\"yellow\"] {\n\t--callout-color: var(--pdf-plus-yellow-rgb);\n   background-color: rgba(var(--callout-color), var(--pdf-plus-highlight-opacity, 0.2))\n}\n.callout[data-callout=\"pdf\"][data-callout-metadata=\"red\"] {\n\t--callout-color: var(--pdf-plus-red-rgb);\n   background-color: rgba(var(--callout-color), var(--pdf-plus-highlight-opacity, 0.2))\n}\n.callout[data-callout=\"pdf\"][data-callout-metadata=\"note\"] {\n\t--callout-color: var(--pdf-plus-note-rgb);\n   background-color: rgba(var(--callout-color), var(--pdf-plus-highlight-opacity, 0.2))\n}\n.callout[data-callout=\"pdf\"][data-callout-metadata=\"important\"] {\n\t--callout-color: var(--pdf-plus-important-rgb);\n   background-color: rgba(var(--callout-color), var(--pdf-plus-highlight-opacity, 0.2))\n}\n.callout[data-callout=\"pdf\"] {\n\t--callout-color: var(--pdf-plus-default-color-rgb);\n   background-color: rgba(var(--callout-color), var(--pdf-plus-highlight-opacity, 0.2))\n}\n.callout[data-callout=\"pdf\"] {\n   --callout-icon: lucide-highlighter;\n}"
}

Error messages

[RyotaUshio]

Thank you a lot for the detailed report! I've fixed it and I will release the new version shortly.

-> Released as 0.39.1.