This looks related to a test case I was preparing to demonstrate how flawed the output from wpautop can get inside lists:

<ol>
<li>
foo

bar
</li>
</ol>

renders as:

<ol> 
<li> 
foo</p> 
<p>bar
</li> 
</ol>

whereas I’d expect it to be

<ol> 
<li> 
<p>foo</p> 
<p>bar</p>
</li> 
</ol>

I’m changing the summary to generally cover wpautop’s problems within <li> elements.