I am using Audacity 3.3.3.
Running under Ventura 13.3.1, on a MacBook Pro 2015.
I made a recording.
Saved it as mp3.
But when I played the mp3, there was no sound.
I tried playing it with, Quicktime, VLC, ILNA, and Music. But there was no sound with any of them.
Incidentally, Audacity Audio Preferences shows Device as: Built-in Output.
And there is no option to select Built-in Input.