TOC error with more than one H1

[Gravy59]

Environment

• Minimal Mistakes version: 4.22.0
• Ruby gem or remote theme version: github-pages 213
• Jekyll version: 3.9.0
• Git repository URL: gravy59/gravy59.github.io
• GitHub Pages hosted (if yes provide URL to site): gravy59.github.io
• Operating system: Windows 10 19042.867 (20H2)

Expected behavior

I just want my TOC to work properly but when I open up the tutorials/stars in blender page the first H1 and beyond is correct but the second H1 and subsequent paragraphs are unformatted. A quick inspection in the compiled html shows that the li is outside of the ul.

Steps to reproduce the behavior

Set up a TOC with more than one H1 (#) and the extra paragraphs are not formatted.

[iBug]

The generated HTML contains quite some strange markup. This needs further investigations.

<nav class="toc">
<header><h4 class="nav__title"><i class="fas fa-clipboard-check"></i> Steps</h4></header>
<ul class="toc__menu">
	<li>
		<a href="#creating-basic-stars">Creating Basic Stars</a>
		<ul>
			<li>
				<a href="#setting-up-the-scene">Setting up the scene</a>
			</li>
			<li>
				<a href="#shading-the-stars">Shading the stars</a>
			</li>
		</ul>
	</li>
</ul>
</li>
<li>
	<a href="#creating-a-milky-way">Creating a Milky Way</a>
	<ul>
		<li>
			<a href="#putting-stars-on-the-milky-way">Putting stars on the Milky Way</a>
		</li>
		<li>
			<a href="#adding-the-milky-way-to-the-scene">Adding the Milky Way to the scene</a>
		</li>
	</ul>
</li>
</ul>
</li>
</ul>
</nav>

For the record, the page is https://gravy59.github.io/tutorials/stars-blender/ (Wayback Machine) and the source file is stars-blender.md (Wayback Machine).

[iBug]

OK not too hard to find out. This is the offending content:

# Creating Basic Stars
### Setting up the scene
### Shading the stars
# Creating a Milky Way
### Putting stars on the Milky Way
### Adding the Milky Way to the scene

You need to use contiguous levels of headings so as not to confuse the TOC generator. "Upgrading" the H3's to H2's produces expected layout for me.

# Creating Basic Stars
## Setting up the scene
## Shading the stars
# Creating a Milky Way
## Putting stars on the Milky Way
## Adding the Milky Way to the scene