I just ran a test and the icon seems to be there and everything is working properly. There is no bug that I can see at this point.
What I can't understand is what went wrong in the case I encountered in my group. I checked and according to the activity log, I did change the member's status to MT before, not after, she sent her first post to the group. How the topic ended up unmoderated is a mystery, but not anything to waste (any more) time on at this point.
Sorry for the false alarm.
Messages are the sole opinion of the author, especially the fishy ones.