RC Passthrough not working on AUX outputs 4&5 on Pixhawk2.1

I am having trouble setting up the RC passthrough function to control servos on Pixhawk2.1 AUX outputs 4 and 5. On Aux outputs 1-3, the passthrough works as expected.

I set the RC_MAP_AUX4 and RC_MAP_AUX5 parameters to the desired RC channels, but those AUX outputs still don’t do anything. They just switch from the PWM_AUX_DISARMED value when disarmed to neutral (or whatever I set PWM_AUX_TRIM4/5 to) when armed.

My airframe is a Quad H, the firmware is the most recent stable release, and I haven’t messed with the airframe mixer. Any idea what could be causing this?

EDIT: Figured it out. The Quad H model uses the “pass” aux mixer, which has AUX outputs 1-3 set up for RC AUX channel passthrough, AUX output 4 set up as flaps/RC mode switch passthrough, and AUX output 5 not set up at all. I assume if I make a new airframe with different aux mix that will take care of it.