I think what your looking for is
(On Key Down)
You are your using
(On Key Pressed)
On Key Pressed = one tick
On key down = multiple ticks
so for crouch
(on Key Down)=Shift > Stop Animations (stops Current Animation)
> Set animation to "Crouch"
> Set Speed (to your liking)
> Start animation From "beginning"
> if needed stop other groups that handle other controls or moves until this ones complete add a wait delay for example below.
Shoty ex by N7Effect, on Flickr
Reload ex by N7Effect, on Flickr
In my example above for Reloading I don't want 'anything' to get in the way of my character reloading until it's end. What you don't see is another group that handles my global variables of ammo. Once the player has shot the gun two times the global variable shuts down the group that allows player to shoot and enables the group allowing reload of weapon. Once weapon Reload animation is complete, Groups go back to default.