Around 12:30PM ET the desktop RC app stopped showing unread message counts for Direct Messages and Teams. The pop-up still occurs, but if you don't click on it in time, then you don't know in which Direct Message or Team chat to go looking for it and all other missed updates.
It's similar to the Oct 13th issues, except today the message are there , but we just don't know new ones arrived or where to look for them.