Original sound for musicians issues - Mac

[hmmassey]

I'm running online singing lessons using a Macbook Air, and always have original sound for musicians enabled so that my voice doesn't cut out and I can play the piano at the same time. Of late - the last month or so - I find my students are complaining they can't hear me. I'm too quiet. I've tried increasing the microphone input, but it's on its max. The automatic adjustment doesn't work either. Am I missing a new setting somewhere? 

[lrac]

Same problem! But it's been on my students end.... even though they have original sound for musicians on, their sound has been completely muted. I found a work around. But extremely frustrating. Does zoom have an answer?