The 'New Posts' selection that I make after logging in selects '1 of 30xx' posts.
I 'marked forums read' all of yesterday's 'new' posts (all 3000+)
This morning, I did my usual routine, logging in and selecting 'New Posts'.
The search engine promptly selected over 3000 new posts, since yesterday.
I know that there have not been that many new posts in less than 24 hrs.

So it's a glitch.

I'll keep trying.

Phil aka tazzman