Agree with CindyReeh's no. 5: I thought that this was just happening on my computer, but I've also noticed that, when I try to go back to a comment so I can edit same, the screen will scroll back up, so I have to keep scrolling to find it.
For me, the biggest drawback is the inability to spell-check all the comments at once, after posting them: I can do so before posting one, but, since I often add many comments to the same document, I prefer to insert them first and then spell-check. I have to do this manually, for ex., changing a word, then waiting for the squiggly red line to show up and choosing a replacement.
Even weirder: though, usually, I am unable to spellcheck comments after the fact, I sometimes can, though I'm limited to whatever replacements are suggested and can't correct a misspelled word manually. As well, when I used MS Word on a borrowed computer, I didn't have this issue,probably because it wasn't the latest version. When I tried editing documents and adding comments in ONeDrive on that same computer, at least misspelt words were flagged, so I could easily catch and correct them. With my poor vision, I often don't even see that a word is misselt.