I was able to fix it by copying the URLs into Notepad2 and rearranging them in there.
I use the drag and drop on occasion. It's useful for browser....sadly it doesn't really work for Thunderbird's RSS reader (I can't drag the URL from the header, neither FFNet or AO3's RSSes have the URL within the message body, and trying to drag it from the message list pastes in the location of the EML file instead) but that's a problem on Thunderbird's end.