After a recent Windows 10 update, to version 1803, my Kinect 2 stopped working properly: it would power off every five or seven seconds, power back up, detect users, then power down again. Basically useless for person tracking.
One could see this just from the white lights on the front of the sensor turning on, then off again.
Scouring the Microsoft Kinect Development forums I found the solution, which is, bizarrely, that you have to keep the microphone on the Kinect enabled.
I share this in case anyone else encounters this:
First check if the audio is disabled from Control Panel -> Hardware and Sound -> Sound -> Recording -> Kinect Microphone. It should be enabled.
Next, open the Microsoft Store Camera app - you will have to physically disconnect or disable any other cameras you may have attached to computer, eg webcam - and under Setting -> Change privacy settings -> Microphone -> Allow apps to access your microphone -> enable the microphone. This should resolve it.
You can verify this visually, and also by using the Kinect Configuration Verifier in the Kinect SDK Browser.
Mark in Brexshit Britain