headers in markdown dont appear as collapsible menu on left sidebar

[armando-fandango]

Describe the bug

context I added level 1,2,3 headers to the Markdown and included it in the index.rst.

conf.py:

html_theme_options = {
    "show_navbar_depth": 3,
    "navigation_depth": 3,
    "show_nav_level": 3,
    "show_toc_level": 3,
...

expectation I expected left side bar to have 3 levels of navigation items in a collapsible menu.

bug But instead only level 1 headers appear. Level 2 and 3 headers are not appearing at all in the left side bar.

$ jupyter-book build mybook
ERROR ...

problem This is a problem for people building the docs from markdown and expecting headers to show up on the left bar.

Reproduce the bug

Use an markdown file and try creating the left side bar with 2-3 level of headers from markdown. Not from toctree declarator.

List your environment

No response

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[eudoxos]

This is (likely) related to #614