Rtl not working

My failsafe is not working properly with I am using rdf 900 radios. I am using a taranis radio . Problem is when I unplug the radio from the ground control the motor will come on for about 10sec and stop nothing changes It stays in whatever flight mode I am in. Also if I would unplug the rdf900 simulating out of range I get no change .If I turn the radio off it will got to rtl.

QGC isn’t really in control of any of those. You should ask on a firmware forum.