Touch bar volume controls don't work I have the MBP 15" model 2017 (macOS High Sierra 10.13.3) with touch bar. What I realized is that the touch bar volume element (mute / unmute / volume up / down) does not work. I press them but nothing happens.

On my apple external keyboard these shortcuts work fine. Also when I try to adjust the volume with the touch bar slider it works like it should.

I tried different things, resetting nvram, removing / adding the controls, killing the control strip, killing the coreaudiod, resetted SMC. but nothing seems to fix it. The only thing that worked is opening a new user account. In the new user account everything seems to be working fine. 

Any ideas of what the problem might be or how it can be fixed?
Seems to be a bug that shows if you plug an external display, etc.

Open Terminal.app and type:

killall ControlStrip