My 450 heli is running on Pixhack 2.8.4 with Arducopter 4.0.5 (heli)., Chibios. The ADSB is missing
in the param even after I connected the uAvionix PingRx to telem port. Attached is the messages tab from MP after powering up Pixhack 2.8.4.
Either you have an old Pixhawk with an early revision processor, that have only 1M flash. A number of features including ADSB is disabled for that board due insufficient memory.
Or you uploaded a wrong firmware version, because of human error or outdated bootloader in pixhack