Jupyter notebook ToC not showing up in rendered post

[bulam]

I noticed for more recent Jupyter notebooks, the ToC is not showing up in the rendered knowledge posts. Older posts seem fine, so a change at some point seems to have broken ToC parsing for jupyer notebooks.

[naoyak]

This looks like it's happening in situations where Markdown cells contain manually written out heading tags rather than Markdown, e.g. <h1>Section heading</h1> rather than ### Section heading. Are there any cases where Markdown headings are improperly processed?