Losing formatting in comments

Just over the past couple of weeks I've had a new issue with Acrobat Pro. I have to include formatting (italics and bold, mostly) in comments and have been doing so for many years. But just recently that formatting has been dropping out. If I quit Acrobat and reopen, I can get it to start accepting formatting again, but it doesn't bring back the formatting that was lost.

For example, I'll have text where I have italicized words and those words are suddenly in plain text. I put the formatting back in and it shows up in the comment box, but when I "post" the comment, the formatting is gone. If I quit and come back, I am successful in getting the italics to hold for the moment, but it may disappear the next time I have the file open.

What can I do to make sure this formatting isn't lost?