For some reason non of my characters crouch, even though I press the right key.
Theres a bit of a delay when you press C. Pressing twice should bring you into the prone position. Check your key setups other than that I don't know what to suggest.
Ok, yes pressing crouch twice will make me go prone, but it's frustrating when I see my NPC team makes crouching half way being less exposed and all I can do is stand.
If I want to go prone, I will press the prone button. Even holding crouch for ten seconds will do nothing.
EDIT: Clone Troopers / Storm Troopers (Which ever is the 'main' unit) can not crouch? I used Sniper, he crouched. But not a normal Clone Trooper?
I'm having the exact same problem.
Hold Still
Press Crouch Button Once
You should crouch after a short delay
You'll stay in crouch till you press the button again.
(It's annoying as heck)