This bug is annoying and I notice it affects every contract I have taken except the objective score part in the contracts. Even worse I have had the get kill, use smoke grenades, (whatever weapon) part of the contract fluctuate. I would have one part of the contract fulfilled only to later have it lower my accomplishment below the needed requirement including it resetting back to zero. Sometimes the contract refuses to even recognize the accomplishment unless I switch to play a different mission type in multiplayer ( going from Walker Assault to Blast, Cargo, etc) even though it is not part of the contract requirement to play in that mode.
As for being able to finally get the accomplishment recognized it has only been because I keep playing trying to fulfill the accomplishment, eventually it happens.
I notice after meeting all requirements that some contracts get stuck reading as if I still need to fulfill a requirement, but at least it did give the reward for completing it. Not sure if this occurs because I take multiple contracts as soon as I am able and the game can't handle multiple contracts taken at the same time which could be causing all the issues involving contracts.