please do the following:
- Use the Steam feature to "Verify integrity of game files". here is a guide on how to do that: https://support.inxile-entertainment.com/hc/en-us/articles/115004662908-Verifying-game-cache-files-Steam

test if that fixed the issue. if not, do the following to cleanly reinstall the mod:
1. close game
2. unsubscribe form the mod
3. start game and enter the main menu
4. close game
5. subscribe to the mod
6. start game