Reporting in during some ESO Hotfix maintenance guys. (My weekend of ESO is riddled with as much fun as ARK... yay!)
One of the hotfixes deployed by WildCard was to prevent a bug where more than the server max of players could join.
This is causing servers to now report as full to everything external, at all stages of server start. Like, Steam, webpages, battlemetrics, etc...
This also means that if you have your server to update when the server is empty during the server boot up, unless you get lucky (No, I have not been able to figure out how one gets lucky in this way) it will not update as the backend here will see the server as full.
Change your server ot always update, reboot, it will update. (Tested on 3 servers now.)