I was wondering others have this problem. I see a comment. There'll be a few replies to that comment and then a roll up of the remaining comments will be there. I'd expect tapping it will unroll the comments. But when I do, the bar changes to a rotating arc icon, and then return to the rolled up status. Which is to say, tapping it doesn't unroll it.
I've seen this only when the comment is from someone I've blocked.
Oh... That could have been it. I connected that when I first blocked someone, but obviously forgot about it. It would be nice to have an indicator like "comment from blocked user" or something.