"JOYSTICK/RC OVERRIDE" or "JOYSTICK/MANUAL CONTROL" how is this determined

I am trying to understand how APM Planner determines whether to forward joystick inputs from a GCS as “JOYSTICK/RC OVERRIDE” or “JOYSTICK/MANUAL CONTROL” as displayed in the APM Planner debug console. There are two simulations I have been comparing using SITL. One with ArduCopter, the other with ArduRover.

When controlling the ArduCopter simulation with APM Planner, “JOYSTICK/RC OVERRIDE” messages as sent. These can control the quad copter in STABILIZE mode. These are also verifiable as Throttle chan3_raw, Yaw chan4_raw, Pitch chan2_raw, Roll chan1_raw messages with MAVLink Inspector.

When controlling the ArduRover simulation with APM Planner, “JOYSTICK/MANUAL CONTROL” messages are sent. These cannot control the rover in MANUAL mode. There are no changes to Throttle chan3_raw, Yaw chan4_raw, Pitch chan2_raw, Roll chan1_raw messages, as expected.

I would like to control the ArduRover using “JOYSTICK/RC OVERRIDE” messages. I have spent some time investigating this and I need some assistance where to look so I can change this behaviour. Your assistance would be much appreciated.

APM Planner Debug message log - SITL/arduCopter
---------------
[20200415 15:54:17.917 DEBUG] - JOYSTICK/RC OVERRIDE: Sent RC override: roll: 1500  pitch: 1500  yaw: 1500  throttle: 1143
[20200415 15:54:18.017 DEBUG] - JOYSTICK/RC OVERRIDE: Sent RC override: roll: 1500  pitch: 1500  yaw: 1500  throttle: 1143
[20200415 15:54:18.118 DEBUG] - JOYSTICK/RC OVERRIDE: Sent RC override: roll: 1500  pitch: 1500  yaw: 1500  throttle: 1143

APM Planner Debug message log - SITL/APMrover2
--------------
[20200415 16:03:27.519 DEBUG] - JOYSTICK/MANUAL CONTROL: SENT MANUAL CONTROL MESSAGE: roll: -1000  pitch: -1000  yaw: -1000  thrust: 0
[20200415 16:03:27.620 DEBUG] - JOYSTICK/MANUAL CONTROL: SENT MANUAL CONTROL MESSAGE: roll: -1000  pitch: -1000  yaw: -1000  thrust: 0
[20200415 16:03:27.720 DEBUG] - JOYSTICK/MANUAL CONTROL: SENT MANUAL CONTROL MESSAGE: roll: -1000  pitch: -1000  yaw: -1000  thrust: 0

For both simulations, the APM Planner debug identifies the Joystick(USB flight controller) as
[20200415 20:39:10.431 INFO ] - 1 input device(s) found:
[20200415 20:39:10.490 INFO ] - - ADC ( 5 Axis, 3 Buttons, 0 Hats )
[20200415 20:39:10.602 INFO ] - Opened “ADC”
[20200415 20:39:31.406 INFO ] - Enabling joystick

APM Planner v2.0.26
SITL
MAV> APM: ArduCopter V4.0.4-dev (1222aa2c)
MAV> APM: ArduRover V4.1.0-dev (1222aa2c)
Ubuntu 16.04
Joystick(USB flight controller) - Esky EK2-0905A