Engineer 3 | Not tracking any of my AA kills

I have finished all the other class challenges, except engineer, going through them all fine until Engineer 3, which refuses to count my AA kills, it counted 2 and then everything else after just isn't counting...

I must have destroyed about 50 helicopters now, using a mixture of Stinger, RPG and MBT LAW, even some kills with the lock-on launcher from AA tank, still nothing.

I've tried: conquest, escalation, tracking, untracking, wearing default engineer skin, switching between them, tracking, shooting heli, untracking and shooting heli, nothing is working. I literally cannot progress this **bleep** assignment. Also tried on real players and bots, official servers and portal.