4 days ago - AndrewT - Direct link
That error log looks bad. There are definitely no mods involved here?

In your clean install, did you make 100% sure there are no files or folders left under either the Steam CK3 or Documents CK3 locations, before installing again?  
4 days ago - AndrewT - Direct link
Possibly, let's see where we are at that point.  
4 days ago - AndrewT - Direct link
If those folders have been untouched for several game versions, it is possible old or corrupted cache folder contents (under Documents) caused this.

Also in the past a bad mod installation may have mucked up the game's installation folder contents.