​​​Setting Mac OS Security Settings for Mojave 10.14 and higher:

​Starting with Mac OS 10.14 Mojave and higher, the Security Preferences want you to allow the “Microphone" for each application. Once you have your USB interface  in System Preferences as your input, it considers that the “microphone" and needs permission on a per app basis.

On Mac OS, click on the Apple Logo in the top left of the screen, go to System Preferences, then to Security & Privacy, then Privacy tab, then Microphone, and          ​check the box for the desired applications to allow audio input (see photos):

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