Did you find a fix for this? I have the same issue
No, unfortunately not. I have explained to the client in advance that it's expected to have these kind of issues with CC, since more attention is put on Projects (at least to my knowledge), but they still decided to go with CC since it's simpler, so for now, we are living with this visual bug.
Ok, thanks for the update :)
Here is a screenshot of comment box for Content Collaboration add-on:
It's added to Assets pane, version is the 22.214.171.12400. Happens on any project I install this on, Alloy or client project.