One channel doesn't record

I’m using a two-channel USB audio interface with MacOS 10.13.6 (High Sierra). Audacity will record the Left channel but not the Right channel. Oddly, GarageBand will record the Right channel but not the Left channel. The audio interface is old (TASCAM US-122 mk2) but this is really strange behavior! Any suggestions?

What’s plugged into the Tascam? Two microphones?

Koz

Are you getting a stereo track recorded with one channel silent? Or are you getting a mono track?

– Bill

I’m just recording solo. One microphone into one channel or the other.