Ideas
Exactly the same problem for me! (still after the recent patch). In this last game I got 2 kills on adrenaline on one challenge and only 1 on the other challenge (one of them was a weekly "all modes" option, the other is the Assault class assignment).
This is particularly annoying because 1) I know I got at least 3 in the game, if not around 5. One of them was a double kill! And 2) I need this to level up assault and get the spawn beacon (one of the more useful gadgets). AND 3! because adrenaline is completely effing useless! you can't hipfire while doing it, you can't break the animation. I've been killed a number of times injecting adrenaline to get this particular stat up, and someone pops around a corner an shoots me. No wonder no one uses it. Also I can't actually tell if it does anything. You'd think it would help, but, personally, I cannot tell the difference. I run about the same speed, it doesn't heal any quicker, I can't shoot any better. what is it for?