First, try a hard reboot of your console.
Hold the power button down for 15 seconds, it'll shut off.
Wait 30 seconds, then turn the Xbox One back on.
Next, make sure there is nothing on top of or above your Kinect. Such as a shelf. The Kinect sensor should be open to the room.
Next, recalibrate your Kinect with the volume of your TV up high.
Finally, make sure you use a normal conversational voice when speaking to your Xbox One. Consider the Xbox One tempermental, but it does not appreciate you shouting at it. It's right there in the room. It can hear you loud and clear (if you calibrate it properly), just talk to it. I know this sounds funny, but it's true.
Xbox One is tempermental about what you say, so make sure you do use the correct phrase for commands, but also the proper cadence. It's Xbox<pause> Help, not Xbox help or worse, Xboxhelp.
To turn the Xbox One off, Xbox: Turn Off. Not Xbox: Off.
I'm not saying you haven't done that, I'm just saying make sure you do it this way.
If a hard boot fixes the problems you were having without any other effort, it's a well known issue. The OS may need a hard boot every now and again to resolve issues, hopefully until Microsoft gets things fixed.
