Bug? Notification counter is not displayed

By Notification counter I mean the following areas:

Today I noticed that the number of unread notifications is not displayed anymore for my user.

I have tested with the following browsers: Pale Moon 27.1.0 (32-bit Windows version), Firefox ESR 45.7.0 (Windows), IE11, Google Chrome Portable 55.0.2883.87 - in none of them I can see currently the number of unread notifications (I have 3 unread notifications in the activity stream at the moment).

Could somebody verify this with a different user/OS browser combination?