Uncommanded Yaw leading to Crash



While flying, I encountered the issue in the log above. As I was flying, the vehicle began to yaw anti-clockwise, followed by a loss of power and responsiveness. In the log above, I attempted to switch the vehicle to stabilized mode to give full power to the motors, however it did not save the quadrotor and did some damage to one landing gear.
This was the second time this type of problem happened. The first (on the same vehicle), I was high enough to recover the 15 meter altitude loss and land safely.

What I’ve found so far: At about 9:05, a yaw deviation started and though the angular rate setpoint moved to correct it, the vehicle did not turn in the correct orientation. According to the UAVCAN measured response of the ESCs, the motors were spinning correctly to counter this yaw.

I know that the vehicle didn’t have a lot of spare thrust (TWR ~1.4 at the time of crash), but what I’m really interested in is why the yaw started and why the reacting motors were unable to stop the system from yawing more. If anyone has any ideas, please let me know.