Did you move or delete your documents folder recently? Or might your PC username have special characters in it? This is an example of the file path the game is looking for:
C:\Users\YOURNAME\OneDrive\Documents\My Games\Company of Heroes 3

Hey I've had this exact same issue from about 2 weeks ago, possibly tied to latest patch and/or a map I downloaded off workshop. Tried verifying game integrity, full uninstall and reinstall, etc. Have had no luck, and other than this post I have not been able to find any other discussion of this issue.

So i have a similar issue atm with trying to play the campaign everytime i start it up the game goes into a loading screen then at 70% loading it just freezes and the game sound keeps playing i have uninstalled , removed mods verified files noting works but i can still play against AI online also when attempting to close the game it stays running even after task manager end task i have to restart the pc everytime 

The problem may be caused by Windows' ransomware protection. On Windows 10, go to Windows security > "Virus & threat protection" > "Ransomware protection" > "Block history". Look whether there "Protected folder access blocked" entries related to RelicCoH3.exe. If that is the case, click on the button "Actions" > "Allow on device".