Toolbar doesn't show up but its buttons work

[TeslaOwls]

Hi,

I've included PDFViewerFX in my project and it seems to work well, with the exception that the toolbar is a ghost.
It works, I can zoom in or out, check the list of pages in the document, print, etc... But it doesn't show up properly

        this.displayer = new PDFDisplayer();
        this.displayer.setSecondaryToolbarToggleVisibility(true);

        this.displayer.loadPDF(new File("C:/somewhere/something.pdf"));

        this.pdfViewAnchorPane.getChildren().add(this.displayer.toNode());

I tried changing my code to the example provided (creating a Scene and putting the Scene in the current Stage) but the result looks identical
Am I missing something or doing something wrong?

Thanks!