Note that there is a difference in the Input settings between “Gamepad Left Stick Left” and “Gamepad Left X”.
"Gamepad Left Stick Left" returns 1 or 0 depending on whether or not the analog stick is tilted left. 1 means you are tilting it left, even if the stick position is .001 left.
"Gamepad Left X" returns a range of values between -1.0 and 1.0 depending on how far left or right you are tilting the analog stick on the controller.
Sounds like you want to be using “Gamepad Left X”, not “Gamepad Left Stick Left”.