Resupply Teammates with the Supply Pouch as Support

Been trying to do the entire Support Specialist challenge series, and the final stage is currently incompleteable. 
Part of the challenge requires you to "Deal damage with the Incendiary Airburst Launcher as Support", however, the Incendiary Airburst Launcher damage you do doesn't track properly. I can camp it for full games without gaining any progress.

I also believe the weapon itself is bugged (or just very undertuned) whenever you fire it, as you almost have to hit point blank shots for you to even do a little amount of damage, and even then the cloud afterwards rarely damages people in the area.