Friendly fire not unlocking?!?!

[Cassog]

hi guys ive completed gears of war 3 on insane, an with 4 player co-op... if i go onto the campaign it says ive done every level 4 player an i have the achievement. The only thing is the friendly fire mutator wont unlock :/ any ideas guys thanks..

[hybridsniper]

Same here . have you had any corrupted save game data at any time ie Rank Resest ?