At my organization, we use Plantronics Headsets to connect to Skype for Business. An employee was having a problem with his -- it would not come off mute. I checked the Sound devices in control panel, and the Skype for Business audio device settings, but nothing was unusual. Then, when that didn't work, I simply uninstalled and reinstalled the driver. It worked fine thereafter.
...then he asked me why that worked. I told him I had no idea. Why does uninstalling and reinstalling drivers fix issues sometimes?