Venu 4 crashes during exercise - 3 times in the last two weeks

During exercise the device has crashed 3 times in the last 2 weeks. 

Symptom: Crash. The screen freezes, no UI updates. The only way to recover the device is by holding down the power button and restarting it.

Cause: Unknown to me.

Misc: I am attempting to follow the garmin coach trainer program.

Software version: 14.12