Notification bell not showing number of new notifications


For some reason on our instance the notification bell icon in the top bar does not show an indicator that new notifications have arrived. So it does not show any number next to the bell, but when I click on it I can see that there are notifications that are new to me (i.e. I have not seen them before nor have interacted with them in any way), but they are already marked as read. Sending a test notification however works and shows up as an unread notification. Real-time updates for notifications are activated and also show up correctly. So not sure what the issue could be and this makes it more difficult to see any new comments, PRs that I have to review etc.

Anyone got any idea how I can figure out what the issue might be?

Some information about the setup, we are running phabricator on ubuntu 16.04 with php 7.1, mysql 5.7.19 and running on the stable branch, release 2017 Week 38.