Singing sound cuts out during meeting

My quartet was singing together in one room for a coach in another state via a Zoom meeting.   Talking was fine but once we started singing, the coach said our sound cut out or only one voice came though.  Both computers were running the latest zoom version and both were set with original sound for musicians, with high fidelity music mode checked and echo cancellation unchecked.   We tried with a Yeti microphone and just with the computer microphone, but neither worked.   Any advice would be greatly appreciated!