FYI
This fixes it:
Close the application you’re using to try and record audio.
On your Mac, choose Apple menu () > System Preferences, then select Security & Privacy, then click Privacy.
In the Privacy window, click Microphone.
Select the checkbox next to an app to allow it to access the built-in microphone on your Mac, an external USB mic, or the inputs on an external audio interface.
Open the app and try to record audio again.
Note: Apple uses “microphone” in this dialog, but the context includes inputs from any audio device. The text within this dialog may vary depending on the audio application.
Cheers,
Gordon