i've been having this bug in my latest playthrough, the rooms save and appear properly for custom empires. but auto generated empires all use this default one: https://i.gyazo.com/4214a46ed7f074515634a4d49c5fffa4.png
i remember this room appeared during the first contact and later diplomacy would show their real one but now they all definetely picked the same room. later i will go through my modlist for conflicts and post if i find anything useful for people with the same error.

EDIT: after testing several games i found the mod that was causing this conflict was Vampire Beast Portraits