Servos jittering on changing flight mode from Stabilize

Hello all,
While conducting a ground run on a 700 dual H3 120 heli running on Ardupilot version 4.2.3, I encountered servo jittering when I changed the flight mode from stabilize to loiter. On further inspection, it was found that the PIXHAWK was providing this periodic pulse to all the servos in flight modes other than ‘stabilize’ as shown in the image below.

Additionally I didn’t face this servo jittering when i reverted the firmware back to 4.1 dev.
Would appreciate if anyone could shed a light on this topic.
Thank you