Recently noticed that in the android app when I return to notifications fron a post that notifications is still showing the post as unread!
This doesn't happen ever time, but about 1 in 6 - enough to be annoying, I might have several that "stick" making it frustrating when reopening the same post.
I can clear all posts as read but not selectively.
Also noticed that occasionally a post will fold back on itself so a block of replies will carryover at the end to be reread.