OpenGL is old and slow and not very well supported by the OSS community any more, Vulkan is newer and faster and better supported.
Please do a full **clean** re-install:
- move any valued save games elsewhere
- "uninstall" in Steam-CK3
- manually delete both the Steam/SteamApps/common/CK3 AND Documents/Paradox Interactive/CK3 folders
- re-install game in Steam, run a Steam Verify when done.
- start the game with no mods active and test
In particular make sure there are no files or folders left under either the Steam CK3 or Documents CK3 locations, before installing again.
**File Locations on Mac OS X**
The executable and DLC folder are in Users/USER/Library/Application Support/Steam/SteamApps/common/Crusader Kings III/
To see it go to the Finder, hit command-shift-G (ie Go To) and type in ~/Library/ .
The user files (settings.txt, error logs, saved games, gfx, mods) are in ...
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