It's happened a couple of times to me now, and I just figured out there must be a time limit on how long the board senses there's no activity and drops your new post search. All of the threads that have new posts are no longer bolded as they were, and the go to first unread post icon has disappeared.

I've been caught out reading very long threads, or following posted links out of FT to read articles, etc., as well as just walking away from the computer for a time.

So how long is the time limit? And can it be extended?

Thanks