I had two games recently with "OUT OF SYNC" problem and the ranking dropped from Diamond 2 8x to Diamond 1 2x , it's totally unfair to me and my partner.

Please investigate in details
In my experience, the ‘out of sync’ problem comes up when I played cross platform ( so xbox-pc or pc-xbox ).
I could not even play between my xbox and my pc, using different accounts and different digital copies of the game, on the same internet connection.