Mac sound control shows USB Audio CODEC with the UCA 202 connected and with audio connected the input level shows incoming audio but nothing passes through to Audacity 3.0.5
Ensure that you have given Audacity permission to access the “microphone” (“microphone” means “any audio input device”)
See: Why do I get a flat line and no sound when I record on Mac?
A million thanks! I had knocked myself out trying everything but that would never have occurred to me.