Co-op Campaign Stuck/Desync Temporary Fix

If your multiplayer coop compaign gets stuck/desyncs then quit and go into C:\Users\Name\AppData\Roaming\The Creative Assembly\Rome2\save_games_multiplayer then get your save and send it to your friend. They must put this in their multiplayer save folder, then you can rehost and this should have fixed it.
You may have to redo this since it will probably happen again until the game is patched.
The game should auto save at the end of each turn so you shouldn't lose any progress.
Hope this helps!