I am now convinced that there is something goofy with the "read" marks on the forum home page and forum group pages. Just now, from the home page, I went into a thread that was marked not all read. Every thread in that forum I had actually read, and it was clear as soon as I got into the forum (all "read" marks showing "read").
Conversely, when I use the "Forum Tools" and select "Mark this forum read", the threads are not marked read (no matter how long I wait).
My approach is to use the forum home page as my jumping off point, so this makes it difficult to track what I've read and what I haven't.
In addition, prehaps also related, I have been noticing that some threads are showing up read even when I don't read them or mark them so.
Lastly, when I post to a thread, the post process places me viewing the end of the thread at my post. However, that thread is not marked read in the forum page. However, if I start a new thread, the new thread is marked read. Ideas?