Alright, I'll give it a go. I can't seem to kill them either. At one point I had them exploding but they stopped for some reason.
I set them to ischaracter = 1 and now they just go through their animations. Every once in a while they'll take a hit and bleed.
Got them set to:
Physics on
Explosion yes
"Don't give up on your dreams, or your dreams will give up on you."- SS <*})))><