3.4.6 - Radio failsafe in AltHold causes direct disarm - bench text

I just upgraded my hexacopter to 3.4.6 and before flying, thought I would test the radio failsafe behaviour on the bench. Connected/powered with only USB (which powers the Rx and GPS quite happily), I went through the following procedure in 3 modes with APM Planner connected and watching the failsafe page (radio failsafe set to RTL):

  1. Arm the copter with the sticks
  2. Raise to 50% throttle (shows in APM Planner)
  3. switch off the radio (Its a Taranis with failsafe set to No Pulses)

The 3 modes and the results as follows:
PosHold - copter switches to RTL and about a minute later disarms, in a later test copter disarmed immediately.
Stabilize - copter switches to RTL and about a minute later disarms, on some tests copter switches to LAND mode and shortly after disarms.
AltHold - copter disarms immediately.

Tried this several times with the above results.
Is the direct disarm likely because it realises it has already landed, therefore no need to go to RTL or land modes? And perhaps in Stabilize, being a non GPS mode?
Just trying to figure if this direct disarm is normal in this bench test scenario, or if there is an issue.

Thanks, Paul

Yes, if it is still landed it will just disarm - it would be dangerous if you were on the ground, for some reason the radio lost connection and it would do a RTL.