Hey Jochen, I am not sure what you mean, things would look funky if you add HTML and miss a closing tag indeed.
Something was turning the:
<ol>into:
<p><</p>
<p>ol></p>if there was no closing tag.
This is not a normal WordPress behavier. But I digged more into the problem, and found that the Markdown module form Jetpack was causing that.
/solved
no Beans issue.
Great, thanks for sharing the solution 🙂