I had a similar problem a while ago: What fixed it for me was:
- Close Steam
- Go to this folder, you may have to show hidden files and folders first.
C:\Users\USERNAME\AppData\LocalLow\Colossal Order\Cities Skylines II
NOW FIRST BACKUP THAT ENTIRE FOLDER! IT CONTAINS YOUR SAVEGAMES!!!!! MAKE THAT BACKUP ON A DIFFERENT DRIVE AND MAKE TWO BACKUPS!
AFTER you have made a backup of the entire folder, you can delete everything inside it EXCEPT the Saves folder.
- Open Steam
- Verify the game files
- Close Steam
- Restart your computer... yes restart... no power saving mode and no cold shutdown. (This should be not necessary but it CANNOT hurt.
- Start Steam.
- Start the game. You should be treated like a brand new installation now.
- Stay in main menu for at least 5 minutes and wait for any mod loading and updating taking place.
- Finished?
- Then go to Mods.
- Create a new Empty Playset.
- Add a few random mods
- Wait for downloads to finish.
- Go back to main menu.
- Exit the game.
- Start the game again. You now should have active mods and no conflicts.
- Start the actual game and start to build your city.
- Everything working?
- Restart the game and create/use your actual mod playset.
Hope that helps.
