I think the CESC onboard log message is the correct one to look at. So for example below is a screen shot of the RPM for the first 2 motors.
The RCOU message will show what is sent to the ESCs but this is different from the feedback from the ESCs.
The issue with the motors not disarming sounds like a bug and we’ve seen similar issues (now fixed) with ToshibaCAN ESCs. I suspect the issue is that the UAVCAN ESC driver expects the output range to the ESCs will be in the range of 1000 to 2000 but that’s not enforced. You should be able to test this by setting MOT_PWM_MIN = 1000, MOT_PWM_MAX = 2000.
I wonder if maybe you could try using MP’s motor test feature to reproduce the issue and test the fix?
I’ve logged an issue here and added it to our Copter-4.0 issues list.