2 months ago - AndrewT - Direct link
Are these Steam Cloud saves perhaps? If so, what if you do local saves instead?  
2 months ago - AndrewT - Direct link
Then this is not a known problem, based on the details you've provided so far. But of course the Linux user base is tiny, and the non-Ubuntu user base even smaller!

Please attach here your Documents/Paradox Interactive/CK3/pdx_settings.txt .
From your Documents/Paradox Interactive/CK3/logs/ folder, attach here system.log , error.log , exceptions.log

Also in Steam please click on Steam-Help-System Info, and paste everything there into a text file and attach that here.  
2 months ago - AndrewT - Direct link
LOcto said: UPDATE: I found the CK3 folder, but the log files are nowhere to be found. I could find just the Save_game_analyzer.gui file and the log_viewer.gui file.
That's probably the Steam-CK3 folder, rather than where the game writes its documents.

The binary and DLC folder by default are in ~/.steam/steam/SteamApps/common/Crusader\ Kings\ III/

The user files (settings.txt, error logs, saved games, gfx, mods) are I think in .local/share/Paradox\ Interactive/Crusader\ Kings\ III/ .