A colleague recently alerted me to an issue she'd had with two separate PDFs, which were created by different people. A few people had added comments and my colleague was trying to delete some of the comments, but whenever she deleted a comment it would momentarily disappear and then pop right back up. Because it was happening on two different PDFs, she assumed it was an issue with her Acrobat settings so she tried it on another computer, but had the same problem. I then also tried to delete comments from one of the PDFs and the same thing happened to me. However, there are other PDFs from which I can delete the comments fine, so I think it must be something to do with the specific files.
We spoke to one of the creators of these PDFs and she said that she had done nothing different in terms of set-up from previous PDFs, on which we haven't had this problem.
Any ideas as to what's going on and how we can fix it? We're both using the up-to-date version of Acrobat DC.