Trouble using mavros /rc/in topic with pixhawk

I’m using a Herelink remote controller which is connected to pixhawk purple-cube via mavlink2 protocol on the telem-2 connector pin. I’m trying to read the rc/in topic in mavros (using rostopic pub).

Command used:
roslaunch mavros apm.launch fcu_url:=serial:///dev/ttyACM0:57600

This is what I can see:
{ header: seq: 71 stamp: secs: 1606131722 nsecs: 352759947 frame_id: ‘’ rssi: 0 channels: [] }

As you can see, none of the 16 channels are visible. No changes in the rc/in channels array occur even with button/stick inputs from the herelink controller.

Do note that communication between the pixhawk and the computer is working well, I ran “rostopic echo /mavros/imu/data” and the appropriate data was being published and could be viewed.