I have completed the entire game and I have not unlocked a single kill related trophy. It feels like some of these levels have had 100s of enemies in them. I have played through the story and then went back to play some of the same levels in arcade and have also done the bonus missions. None of these have helped me unlock any of the kill trophies. It seems like it is glitched but I am wondering if there is a catch to it and the kills are in a certain game mode or something?