Please do a full clean re-install:
- move any valued save games elsewhere
- "uninstall" in Steam-Vic3
- manually delete both the Steam/SteamApps/common/Victoria3 AND Documents/Paradox Interactive/Victoria3 folders - In particular make sure there are no files or folders left under either the Steam Victoria3 or Documents Victoria3 locations, before installing again.
- re-install game in Steam, run a Steam Verify when done.
- test with a new unmodded campaign, NOT any existing one
If those don't help:
Please attach here your Documents/Paradox Interactive/Victoria3/pdx_settings.json .
From your Documents/Paradox Interactive/Victoria3/logs/ folder, attach here system.log , error.log
From your Documents/Paradox Interactive/Victoria3/crashes/ folder, attach here the latest (only!) exceptions.txt
Also in Steam please click on Steam-Help-System Info, and paste everything there into a text file and attach that here.
**File Locations on Mac OS X**
The executable and DLC folder are in Users/USER/Library/Application Support/Steam/SteamApps/common/Victoria3/
To see it go to the Finder, hit command-shift-G (ie Go To) and type in ~/Library/ .
The user files (settings files, error logs, saved games, mods) are in /Users/USER/Documents/Paradox Interactive/Victoria3/ .