In my experience, Group Respawn is notoriously bad for transferring any kind of function.
Radio Support, Support Request (Vanilla game), High Command etc.
This has been the case since ArmA2.
There are workarounds, I remember managing a script that transferred High Command in ArmA2, but it wasn't super easy.
You had to "createUnit" new modules via a script and synch them correctly to the new units, and repeat the process after every death.
For OK transfer of these type of functions to a new unit after respawn, I would recommend using regular respawn (with respawn positions).
Not as immersive in my opinion, but it works better technically.
Someone might have a good workaround, but I haven't found one yet.
Cheers,
Laggy