Never had issues playing Shogun 2 and have been playing for years. Hadn't played in a bit and since this last patch where the mod menu broke, it seems the campaign desyncs and breaks down within 20 turns and does it nonstop despite whatever you do.

Tried many solutions suggested by Sega support and they recommended to come here. 

I understanding sending my save file to my friend "fixes" it, but I'm looking for a real fix, not something I need to do every 10 turns.