Halo 5 ranking

This game keeps telling me that i need one game to get onyx after i lost it i won the game but it didn’t even bring the rank up i played another game lost then they gave me diamond 5 i just won the game needed to get diamond6 but again it didnt even bring my rank up a little can someone tell me whats happening?

There’s a matchmaking feedback thread pinned in the MM section of the forums.

READ THE OP BEFORE POSTING.