Hello Laura and welcome to the Cow Audio Forum.
USB audio devices are not considered “professional” so not many here may have had much experience with them.
I have several thoughts.
1. Sometimes the USB device requires power from the computer that may not be available at a hub. Plug directly into the MBP.
2. Audacity requires that you choose what input it will receive. That may be in the Audacity preference panel or on the Audacity interface itself. (and I’m sure in its instructions).
3. After plugging the mic in, also visit the Mac Sound System Preferences panel and choose the USB mic for input.
4. If this works, try inserting the hub in the chain if you need it.
Regards,
Ty Ford
Cow Audio Forum Leader
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