Logitech H390 headset in Mac OS X 10.11.5 suddenly listed as "Lync audio device"

Hi guys,

from one day to another my Logitech H390 USB headset stopped working. When checking in system settings / audio, I discovered that strangely it is not listed as "Logitech audio device" anymore but instead as "Lync audio device". Have tested on Mac OS X 10.11.4 & .5 on MacBook Air 13" and Mac mini. Any idea what is causing that sudden change in not recognizing the Logitech headset any more? I have googled about the phenomena and saw that others are affected, too. But no solution found yet.

Any help is appreciated highly – thanks in advance!

Cheers, Marc