Microphone.Start throws an error with Kinect V2

Using Microphone.Start with a Kinect V2 microphone set as default recording device on Windows 8.1 throws an error:

Starting Microphone failed. result=25 (Unsupported file or audio format. ) UnityEngine.Microphone:Start(String, Boolean, Int32, Int32)

I used it this way:

Microphone.Start(null, true, 100, 16000);

I'm using Unity 5.4.2f2. The same code worked on Unity 5.3.4f1 and still works on Unity 5.4.2f2 if I use a standard microphone connected to the jack port of the PC.

Do you know how to solve it?