Relay function does not work on AUX1 (GPIO 50) and AUX2 (GPIO 51) on Pixhawk board

The setup is a camera trigger via the relay method.
The firmware is Arducopter latest release (as of today).
The test configuration is the following:
-BRD_PWM_COUNT set to 0 (so all of the 6 AUX outputs can be used as GPIO for relay)
-Camera trigger type set to relay
-Relay 1 set to GPIO 50 (AUX1) - I also tested with Relay 1 set to GPIO 51 (AUX2)
-Camera cable connected to AUX1

Test is using mission planner “Trigger now” function on the world map.

Result : nothing happens.

If i test with Relay 1 set to GPIO 52 (or 53, 54, 55), it works.

So is there a bug in the firmware that does not allow to use the first two AUX ports as relay outputs ?

This works fine for me. CAM_TRIGG_TYPE set to 1?

BRD_PWM_COUNT to 0
RELAY_PIN to 50

Trigger from Camera NOW and monitor aux 1 Output with meter.