Only hear audio from Audio 1. I can see waveforms in the Audio 2 but no bars. PLEASE HELP!

I'm editing a multicam sequence and can only hear audio from Audio 1. I can see waveforms in the Audio 2, but there are no audio bars. When I solo the audio track, there is no sound.

I can hear audio 1, so no output issue.

Shot on a Canon R5 C - back in December (!) so with it being so long ago I cant remember if I set the audio as seperated in the CH1/CH2 ALC Link settings, perhaps I combined the audio? But my fear is that I've not turned on his mic, and in testing it was the second guys mic picking up his audio as they are sat so close.

Spec 

Premiere 23.2.0 
Editing on a

Macbook Pro 2021

OS Monterey 12.2.1

Chip: Apple M1 Pro 16GB 

Thanks so much