Normally, when I sign on, any posts that have been made to topics that I've commented on will trigger a numeric count next to the Communications button top right of the screen. I click on Communications and the posts in questions are in order at the top of the list.
Last week or so I had 4 items in my "Communications" file that I couldn't find. I would clean out my unread messages at the top and there would still be a "4" next to Communications. I checked with the Community Manager about this issue. He suggested I check the box that is "unread only" in the Communications Section. It worked. There were 4 messages that showed up as unread from 5 months ago. I didn't see any new activity on these threads, but was able to click them open and get rid of the "4'.
Just an FYI for anyone else having the same problem.