This has been happening on and off, what feels like randomly (I know tech people hate that word, but I haven't been able to discern a pattern or correlation of any sort). Some threads, usually ones that were quiet for a few days, get resurrected by late comments. And sometimes (I don't think it's all the time) these are appearing to me as completely unread, despite sometimes bearing comments of mine from earlier days. I've experienced this for more than a month now, off and on, but I don't see anyone else talking about it. Is this a known bug?