Hi Spike. Not sure if this is relevant, but I don't seem to get notifications of replies to posts or comments I make in groups like I do to comments and posts in the forums. That's caused me to miss replies in the past. I'm not sure if this is standard behaviour for groups on this platform, or something I've missed / got wrong in the way I've set up my notification preferences, to be honest.
When I visit I do see new posts though, so haven't had the problem you've experienced.