Assault 1 - Adrenaline Injector Task

The task does not seem to track appropriately, only seems to track if you pop the adrenaline and kill someone within a second of it being activated, I noticed this after playing 2 games and killing lots of people with it and seeing that my progress was at 2. I tried it again and noticed that if they are not killed within a second of activating it does not register despite the effect lasting several seconds.

Thanks