RC Passthrough to Control Servo

Currently working on a payload drop servo controlled by a switch on my remote. I want to do a RC channel passthrough on AUX5 with an Orange Cube. “payloads and cameras” from PX4 documentation states “map up to three RC channels to control servos/actuators attached to the flight controller using the parameters RC_MAP_AUX1 to RC_MAP_AUX3.” Obviously, AUX5 is not default setup to be a passthrough pwm output. I have been able to get the cube to output pwm signals to my servo but no luck with controlling it through the switch. It doesn’t seem to be as simple as modifying my airframe’s mixer and assigning my RC channel to “RC_MAP_AUX5”. Does anyone have any suggestions, similar issues, justification for why passthrough won’t work on AUX5?