Loss of power and logging stopping

I have used Firmware Version V4.4.0-beta2 dshot on matek 405-vtol which is the 405te build.
Had great results on a Hee Wing T1 VTOL, qhover,rth with conversion all working perfectly.
However on my last flight I had video loss, after inspection it seems I lost power and plane glided down into next field. Power loss was not loss of battery as I still had RX telemetry and GPS data was valid for where plane landed. Looking at blackbox logs it seems that logging stopped when I lost video.
Any ideas on what to check or what could cause this.

Size (kb) 1397.4921875
No of lines 16199
Duration 0:00:12
Vehicletype ArduPlane
Firmware Version V4.4.0-beta2
Firmware Hash 602f7d13
Hardware Type
Free Mem 0
Skipped Lines 146
Test: Autotune = NA -
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (12.09%)

Test: Dupe Log Data = GOOD -
Test: Empty = FAIL - Empty log? Throttle never above 20%
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: IMU Mismatch = NA -
Test: Motor Balance = NA -
Test: NaNs = FAIL - Found NaN in POWR.Vcc
Found NaN in POWR.VServo

Test: OpticalFlow = FAIL - ‘FLOW_FXSCALER’ not found
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC = UNKNOWN - No CURR log data

Not sure how to attach log