'is_armable' parameter doesn't change, Dronekit-python

I am currently building dronekit script to control my drone with computer
I successfully connected to drone via USB port and I am trying to update all the parameters that I need regularly. everything seems to be working fine. but ‘vehicle.is_armable’ doesn’t return ‘True’ even if I can arm with RC transmitter. if I make my copter armed via RC, ‘vehicle.armed’ command returns ‘True’ but ‘is_armable’ parameter stays the same… ‘False’…
I cannot figure out what is wrong… please help
Thank you in advance!

Its been a year… Did you get a solution? I am having the same problem. Even though vehicle.is_armable is False, I can arm by vehicle.armed=True and also with RC. Should I just ignore it?