22 days ago - Juber - Direct link
Sorry for the delay, I finally could find our the root cause and also reproduce it.
The thing is, it is a bit different then observed and this report is only a result of the bug. Let me explain:
The Taverns are actually full, even if they are displayed as not full. This happens, when you are not in your city (for example in the GE or gbg) and other players visit the tavern during this time. When you come back, the symbol did not update for you, even if the tavern was filled during that time. If you click on the symbol, it will refresh and now show, that the tavern is actually already full. You can see that, if you click on the symbol again and then notice, that you are actually not in the tavern.
The same is the case when the tavern was full and the owner collected their tavern silver. It will still be displayed as full in the friends list, even if it is not anymore.
I have reported it now to the devs. Thank you for the report!