Here, I just got to the bottom of a thread, and it says there is 1 new topic remaining:
I ignore it and click through to one of the suggested topics:
Note that the number of unread topics has refreshed itself.
And again, no matter how many suggested topics I click through, or visits to the Unread view, it continues to claim that there is 1 new topic remaining, but when I actually click on the “1 new” link…
I’d guess that it has something to do with browsing on different systems, and maybe there was a new topic that I viewed on another system that threw it off. Not a huge problem, but hopefully low-hanging fruit to fix – it’s already querying the server for the current “unread” count, and presumably it should be getting the “new” count at the same time.