Plane Launch through Catapult in FWBA mode and takeoff was normal but when mode shift to Auto, throttle dropped to zero

I launch my 7kg plane through catapult, currently i am not using acceleration and speed checks for auto arming. I lauched the plane in FBWA mode, take off was normal as i increased the throttle to 100% as soon as it left the catapult and ground speed also increased above 20m/s but as soon as i shifted the mode to AUTO, throttle dropped to zero and my plane crashed.
i have not found any reason in my log, if any one can help to dig out the problem.
log bin file is here >> https://drive.google.com/file/d/1MuF4PKa3Cy_taVgV1dUlsD7pIowIAnbH/view?usp=drive_link