It seems the 20XP is causing some headaches for Gears players. Some matches seem to have it others do not. It seems that you must restart your xbox for the updated playlists to take effect. The kicker is that if the host of the game hasnt reset their xbox and you join their game you wont get the 20XP!
ALL UK GEARS PLAYERS, RESET YOUR XBOX’S IF YOU STARTED PLAYING BEFORE 5PM!