Help! Can't hear playback inside Audition

I'm recording in Audition 2023. 

Mono in multitrack.

OS = Big Sur

My recordings won't play back inside audition. I can see the waveform in audition and playback the .wav by clicking on the file in my finder. But that's it.

Settings are Input: External interface (behringer u-phoria umc202) and Output: internal speakers (System pref for sound match the settings in Audition).

I've tried restarting - didn't help.

I'm a VO artist with an audition due tomorrow. Help please!