almost 4 years ago - AndrewT - Direct link
So the launcher itself seems okay? Is it the current version 2020.16 or something else?

Can you run the game with ck3.exe directly from Windows Explorer? If not, DXDIAG is a program you run from a command prompt or the Windows start menu 'run' dialog box (or 'search programs' in Windows 7 or later). After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.

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