over 2 years ago - AndrewT - Direct link
Are you 100% sure there were no files or folders left under either the Steam CK3 or Documents CK3 locations, before installing again?  
almost 2 years ago - AndrewT - Direct link
DXDIAG is a program you run from the Windows search box on the task bar. 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 here your Documents/Paradox Interactive/CK3/pdx_settings.txt .
From your Documents/Paradox Interactive/CK3/logs/ folder, attach here system.log , error.log