Well let me clarify. I lost my campaign saves long long ago. As I said this problem has persisted for at least 2 years and I've reinstalled the game and done the Steam verify files many times. This nuked all my campaign saves. As for the saves I tried the other day they were for Scenario maps since all I can do is play short scenarios since I couldn't load saves.

Well my game clearly doesn't care. "1 files failed to validate and will be reacquired." which is the classic Steam issue that translates to "Everything was fine."