Built in Output set to mute when Input configured with USB Mic
I have a USB microphone that when plugged in sets my macOS built in output to mute.
When this occurs the mute action descreases in increments until it hits zero at which stage the mute display is permanently visible on the screen and it is not pssible to umute the output with the USB mic plugged in.
I have my Sound Output set to Built In
I have my Sound Input set to USB Mic
I've tried creating an aggregate device in Audio MIDI Setup which made no change.