Consistent Multiplayer Campaign Desynchronisation (in battles, not on the map)

[LSD]

I've been playing the Multiplayer Campaign recently, and both me and my campaign partner suffer desynchs in EVERY single battle we try to play; however, naval battles and normal multiplayer battles work perfectly fine.

Any ideas as to why this is? We've played one Multiplayer Campaign naval battle together, which worked fine. We played about 3-4 normal multiplayer battles (with other players, too) which worked perfectly fine.

We found that my own autosave for the Multiplayer Campaign was (very slightly) smaller in size, so i tried sending him a copy of my own file -- that didn't work either. Neither the European nor Spanish Multiplayer Campaign works for us.

[LSD]

Any word on this? Or anything that might work? I've so far played about 50 games with my multiplayer partner -- scenario battles, naval battles, land battles, siege battles. They all work perfectly fine, yet land battles in the multiplayer campaign don't work at all.

Is there really nothing we can do about this?