Deleted and reinstalled. I got this debug file:
Debug Message: Command Line:
Debug Message: Personal folder located at C:\Users\nimzo\OneDrive\Documents
Debug Message: There was a problem accessing your Galactic Civilizations IV: Supernova user data folder. Error: The system cannot find the file specified.
.
Please see our troubleshooting guide or post on our support forum for assistance.
...
It is looking on OneDrive instead of my C drive.