I’m quite surprised you are not getting an echo in the room from such a grouped setup with TV audio (but should work fine for Music audio)  - Anyhow, there is a ‘Group Audio Delay’ option in the Sonos App in ‘Settings/System/nBeam Room Name]’ that is designed to increase the audio buffer between grouped rooms, so perhaps try that to eliminate your audio dropout on the Move.

Thank you. 

I adjusted the audio delay, larger & back to smaller and it seemed to reset itself and work again. I have not experienced any echo, perhaps because I rely on Sonos for sound with silence from the TV.

Thanks for your help.