Crouch and Un Crouch built in functions not working properly?

I’m trying to use the “Crouch” and “Un Crouch” functions in my FPS game so that I can avoid players falling off ledges while crouched. However, they don’t seem to be doing anything. When I press the crouch button, the movement speed slows, but the camera doesn’t move anywhere unless I have more stuff attached as shown below.

When that is all set up as shown, the camera moves, but the movement itself is jittery. It looks like it jumps up slightly before it actually crouches. I just want to make it so that players can crouch to not fall off ledges, how can I do this?