I´m currently wrestling with a set of Kontronik ESCs, trying to get them calibrated on a Pixhawk 4 with copter 3.6.1 flashed.
The ESCs can be teached offboard with a servotester, they operate just fine - but they don´t reply in any way when connected to the Pixhawk.
It seems to me that they need at least some kind of PWM input to start up; input, they obviusly don´t get when not armed.
Did anyone experience similar problems with an ESC? What´s a proper solution for this…?
Even if not armed pixhawk is sending out pwm, otherwise escs would not initialize.
Do the escs make the initialize sound or keep beeping like no pwm available?
They DIDN´T make any sound - but currently, I´ve fixed the problem 
Or to be more precise, it somehow solved itself, quite unsatisfying.
One major step was, that´s for sure, to keep the GPS and pixhawk unit still while initialising. Moving one of those components will delay and eventually terminate the startup sequence of the ESCs…