Offboard control using gamepad

Im using CUAV V5 with PX4 and Raspberry Pi and im trying to get offboard control using a gamepad to work.

If i set COM_RC_MODE_IN to JOYSTCK/NO RC CHECKS I have full control of the vehicle from taking off to landing. But im also wanting a transmitter to use as a safety backup.

If i set COM_RC_MODE_IN to RC TRANSMITTER I can only arm the drone using the gamepad. I cannot enter Offboard Mode when using the switch. What should the COM_RC_MODE_IN parameter be set to so I can use both the Transmitter and gamepad. From what I have read I should be able to arm the drone with the transmitter and switch to offboard mode to take control with the gamepad.