Sometimes it shows "1 new notification" or higher but it's old. You can't get rid of it. Thats 1
2: and could be related, it will not show new replies to you, so my guess is, the system shows you "new notification" (red mark) but the new notification is not there, you can not see it. I sometimes see replies to me but did not get a notification. obviously this has happened to me already multiple times, I'm just reporting it now.