Dual motors tailsitter

need some help
skywalker x5 tailsitter vector motor.
servo1,2 elevon, servo3,4 tilt servo, servo5,6 ESC. micro pixhawk with arduplane plane v4.0.5

problem: power x5 safety button on (solid led) DISARM , if RC TX flight mode switch at FBWA position and power on TX then two motors start spin raise TX throttle motor no reaction. swith to other VTOL mode motor stop. don’t understand why motor spin under FBWA mold and disarm.