Battle Buddies
Complete the campaign in Co-op

I played with my friend in Coop ELITE mode and finished all the levels just few hours ago.
But don't know why that I can't get this "Battle Buddies" trophy.
It's very sad. I have to play again to get it.
But I checked it's not my problem so any UBI tech could tell me why or what's going on ?!
Thank you soooo much !!!