Crash not detected in takeoff mode

My plane belly-flopped hard into the ground about 2 seconds after takeoff (while in TAKEOFF mode). ArduPlane 4.1.6 didn’t detect the crash, didn’t disarm the thrusters - plane bounced and continued to fly.

Parameters were set as follows:
CRASH_ACC_THRESH, Value : 25.0
CRASH_DETECT, Value : 1.0

Plane’s Pixhawk has two IMUs. Flight logs show IMU.accX exceeding -27 m/s/s at time of belly-flop for both IMU[0] and IMU[1]. Why didn’t ArduPlane disable the thrusters? Logs show plane was in TAKEOFF mode, which I assume is an “auto” mode, correct? Documentation seems to say that motors should have been disabled with these parameters and these IMU.accX values in this mode. Yet motors continued to run - why? Logged STATUS messages show Crashed and Hit always equal to 0. Thanks!

I think I understand why crash was not detected. Documentation states “Automatic takeoff can be accomplished either as a mission control command or by directly changing into the TAKEOFF mode.” In my case, I directly changed into TAKEOFF mode, i.e. not as a mission command. Documentation also states that crash detection is only provided in AUTO mode. I presume that directly changing to TAKEOFF mode is not AUTO mode - but the documentation isn’t clear about this. What does everyone think?