Version 3.3.3. I've found several anomalies in the behavior of nested markdown=1 blocks. Here's one that's probably diagnostic:

markdown.markdown('<div class="outer" markdown="block"><div class="inner" markdown="block">*foo*</div></div>', extensions=["extra"])

returns:

'<p><div class="inner" markdown="block"><div class="outer" markdown="block">*foo*</div></p>\n</div>'

The inner <div> is now outside.

Other weird things in this example are the addition of the <p> tags, which are unmatched, and a stray \n .