I suspect that the Tableau Server that is running on-premise may not be configured to have direct internet access so the server can reach the Tableau Mapping Servers. That can limit the zoom levels of maps.
I'm just taking a stab in the dark as I have seen several customers run into mapping issues only to find that the admin did not realize the server has to have access to the internet for proper mapping. Usually it is a firewall issue and the proper ports need to be opened as well as a whitelist created. If company policy is to block internet access, then an internal WMS server would solve the problem.
So a bit of research on the internal workings of how your Tableau Server was set up.