Johny.: Forum algorithm for making post replies and sending the notification is the same, but the forum reply "in-bell-notification" is cleared as soon as you enter/refresh the topic in which it appeared. Which might not be the case for the in-forum counting (conditions for clearing the count might be different).
Yes - they have expiration date set, I see it's 1 month now for forum reply notification, but it should be 13 months really (I've reported it now) as it's for other notifications.
Did anyone act on your report, and made the expiration date even shorter instead of longer?
I'm now missing a notification for a forum reply that's just a couple/few days old. And no, it's not a case of having visited the thread; I haven't, plus that would have also cleared the little gear on the forum, and that's clearly still there.
I also got no count for new notifications since I last was on, among them for a new chat message.
Perhaps this is all related to the recent "bell flashing and clearing at every page load" bug reported by multiple people in the "what did just break" thread. Fact is, notifications aren't working as should.
Long live BE.