Have you attempted to disable the cloud sync in the STEAM settings? So make sure all the local files are gone, including the configuration files stored locally.

You could also try all of this on the same machine, by simply creating yourself another local admin account in Windows.

From that STEAM instance, you could make sure the sync settings are disabled before you launch the game. You shouldn't be required to download all the data files again, as the library files follow the computer and not the user profile.

Once you get things configured correctly, and if the game runs fine, then re-enable your cloud sync, and hopefully you will get a message telling you there is a change between the local and the cloud configs.

Good luck