When hosting mods that use custom UIs (e.g. Gloomhaven - Fantasy Setup), we noticed a strange bug with my group. Players joining a server hosted by me cannot see the custom UI elements and cannot change object states from the context menu. In the mod referenced above, this would mean that the "initiative tracker" and "game setup" buttons don't appear, the rule book and scenario book cannot be opened, and health bars and status effects are not visible above figurines. The same problem appears in other mods too, but only those using a custom UI. When anybody else from the group hosted the same mods, the games worked well for all others, but the problem occurred only for me.

After some experimenting and talking to other players, it appears the problem is somehow related to language settings. I noticed that the problem did not occur between Hungarian players but it does occur for non-Hungarians joining a server hosted by a Hungarian, or for Hungarians joining a server hosted by a non-Hungarian. Other Hungarian players have confirmed that they have experienced the same issue in various mods that use custom UIs, it’s not limited to me.

The problem persists both in Windows 7 and 10, tried two different computers.