Refer to attachment.

Seemingly overnight, all threads/posts at the subforum index are indicated as unread (new), when they aren't. Visiting any of the subforums confirms that they aren't new.

I've tried deleting cookies, clearing browser and ubb.t cache, and no dice.

I'm not sure if this is a "bug" or just a weird state I've found myself in? Any ideas?
Attachments
562-vfdc_posts_unread.PNG