That thing happened last night (due to lag from the sudden heavy traffic) and has been fixed since.
You must make sure the mark as read worked before leaving the pm box.
It's not fixed. It happened to my inbox right now.
You need to mark them as read and only after the green border (left side of the box) is gone you can leave the page.
Also if someone replies to a post/comment and deletes a few second later, the notification will persist.
Do I have "mentally impaired" written on my profile?
I am saying old posts are marked as new.
I repeat. I have old posts marked as new again as false new posts.
It's happening right now with your post.
(post is archived)