More trouble with RSS2 feed

I, too, am having trouble with my podcast feed. I was running 1.5 and knew the response would be ‘Upgrade!’ So I did, to 1.5.2, but still my latest feed won’t go out.

Can someone in the know please look over the feed
https://audiolingo.org/wp-rss2.php
and tell me if they see any glaring errors? I tried ditching the old mp3 file and creating a new one, to no avail.