Flyaway, RC connection lost?

Hi, Have experienced flyaway today. Just after takeoff I’ve lost RC control, and it was flyingaway.
quad, with pixhawk, 3.2.1
was builded by myself, and was flying successfully not many times before in stabilise mode, RTL mode worked perfectly earlier - it was activated automatically when voltage from battery fall below 10.1V
just before load deviation SW in my Devo 7E
Would be very appreciate for any help, comments or suggestions.
Log attached.

Thank you.

Here is an Auto Analysis of your dataflash log:

Size (kb) 1523.7236328125
No of lines 20246
Duration 0:01:46
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = FAIL - Truncated Log? Ends while armed at altitude 3.36m
Test: Compass = GOOD - No MAG data, unable to test mag_field interference

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.21, WARN: 0.75, FAIL: 1.50)
Test: Parameters = GOOD -
Test: PM = FAIL - 10 slow loop lines found, max 9.30% on line 1405
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = GOOD -


Please more comments - I’ve done this analysis before.
Brownout = FAIL - Truncated Log? Ends while armed at altitude 3.36m - looks like battery was disconnected, fortunately - that is why I’ve found my quad, or did you mean something else?
Thank you, anywhere.

Did you not have a loss of RC signal failsafe setup to RTL?

You are absolutely right - seems like RC range decreased significantly after software upgrade. Failsafe was not setup for this case. Thank you a lot.