Hmm, that suggests the recording device is not actually set to the microphone, if the Voice Chat settings in the Battle.net app are testing the “System Default Device”.
Let’s check what’s going on there.
- Hit Windows key and type sound.
- In the filtered search results, select the Control Panel item for Sound.
- Go to the Recording tab.
- Check which device is set as the Default Device. It should be your headset microphone.
- If you see the Stereo Mix device in the light, right-click it and select Disable.
Retest the microphone in the Battle.net voice chat after that.