Matek F765 with Matek GPS Failure

I am uploading two flight logs from the memorial day weekend (Saturday and Monday).

Maiden flight was conducted on Saturday 5/23. Two flights went flawlessly.

Monday flight crashed with the plane making a 45-degree descend. No elevator response, the plane was in FBWA mode.

Please review the file dated 5/25/2020. What I can tell from the log file is that the Hdope went from 1.3 to 0.0. But what I don’t understand is why would it descend if there was a GPS failure?

FW: Arduplane 4.0.5
HW: Matek F765 + Matek GPS with Compass.
Receiver: R9 Mini

Log analyzer: Saturday 5/23 flight log
Log File C:\Users\htsyed\Documents\Mission Planner\logs\FIXED_WING\1\2020-05-23 09-18-06.log
Size (kb) 34884.0703125
No of lines 457127
Duration 0:09:14
Vehicletype ArduPlane
Firmware Version V4.0.5
Firmware Hash 0bfa2638
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = NA -
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (22.89%)
Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: IMU Mismatch = FAIL - Check vibration or accelerometer calibration. (Mismatch: 1.97, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = NA -
Test: NaNs = FAIL - Found NaN in POS.RelOriginAlt
Test: OpticalFlow = FAIL - FAIL: no optical flow data
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC = UNKNOWN - No CURR log data

Monday 5/25/2020 flight analyzer
Log File C:\Users\htsyed\Documents\Mission Planner\logs\FIXED_WING\1\2020-05-25 11-29-51.log
Size (kb) 13566.8603515625
No of lines 176666
Duration 0:03:33
Vehicletype ArduPlane
Firmware Version V4.0.5
Firmware Hash 0bfa2638
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = NA -
Test: Brownout = GOOD -
Test: Compass = WARN - Moderate change in mag_field (26.61%)
Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: IMU Mismatch = WARN - Check vibration or accelerometer calibration. (Mismatch: 1.44, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = NA -
Test: NaNs = FAIL - Found NaN in POS.RelOriginAlt
Test: OpticalFlow = FAIL - FAIL: no optical flow data
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC = UNKNOWN - No CURR log data