Thanks for the follow-up from both of you. Are you having this problem with all of your PMs or is it for ones that maybe have a really long, unbroken string of characters in them for some reason? We've had formatting issues with thread titles containing words that that were long and unbroken, so I was wondering if it might be related.
The longer they got, I finally couldn't even see any of the reply button when trying to read. If I hit the reply button I could read everything a squished together. Maybe try a test PM back and forth with myself or VirginiaBred and see what it looks like on your side. I had one, now deleted, with okggo and finally had to start a new PM because I literally couldn't reply.
FYI, in mine we left the original PMs in there in quotes so not sure what the system is doing to them.