This may only work if you purchased the game through the microsoft store! Also this will reset you at your current mission and you will lose checkpoints or at least I did. But this is way better than restarting your entire campaign!
Delete the first 2 documents and then restart the application! & continue campaign and it should work like it did for me!
As soon as I read that some people had corrupted saves I started looking for a safety measure. Couldn’t find one by myself but the community came to the rescue.
An auto save system without the possibility to manually save into a different slot means your only backup is manually copying those sneaky files and store them somewhere else. Save locations for both Steam and Win Store versions.