Pixhack v5 AUX servo jitter

I’m on the CUAV Pixhack v5

I’m seeing an issue where if I connect a servo to the AUX pins and send a 1500us PWM signal (using “pwm test -c 13456 -p 1500 -d /dev/pwm_output1”) I get significant jitter in the servo moving all over the place.

When I do the same test on the MAIN pins the servo are centered and steady.

Has anyone run into this?