I'd still suggest trying using a different usb controller/Gamepad
How is the SN30 connected to the PI? is it USB cable or Bluetooth?
Here's some stuff to try, might not do anything at all.. but it's worth a try..
If it's the wired version. Turn on your PI and boot up, unplug the controller now press the Y button while plugging back in the SN30.
then see if works... Do the same but pressing the X button.
Y should set it to "switch" mode and X to "PC mode", the type of controller that it detects should change, when you do this, see if it makes any difference.