Challenges not tracking

Another challenge not tracking would be the Engineer tier 3 "deal 1000 damage to laser designated vehicles with lock-on guided weapons."

I have been using the anti-air lock on launcher--the first one you get (SLM-93A Spire). Been using it against helis and jets. I've had friends as recon designate aircraft for me, taken down a few, and for some reason the challenge seems to be stuck at 113/1000 damage. I've been doing this primarily on the Mirak Valley, Liberation Peak, and New Sobek City maps.

I also have tried to use this same launcher against laser designated tanks and other ground vehicles, but the missile/projectile itself completely missed it's target every time I have tried this kind of attempt.