Ok, this is a little annoying, but it's only affecting one thread.
The "Completed Fanfic Recommendations" WILL NOT mark itself as "read" for me, no matter how many times I go into it. It still shows as having new unread posts.
have you tried marking the entire forum read?
I still don't have a handle on many of the inner workings of MyBB yet, so while I could manually toggle the appropriate setting for you in the database, I'm currently unable to actually track what's going wrong for you through the actual board software.
That said, Rob's suggestion is worth a try.
Yeah, I was having the same problem. One thread I had read several times in There's Nothing Better forum was always showing up as unread. Marking the whole forum read resolved that problem for me.
Marking the whole forum read did in fact mark the thread as read. I guess I'll wait and see what happens next time someone posts in it.
I think the forum upgrade resolved this problem. I kept a weird forum in its partially read state, but it cleared unread by reading threads normally.