Nanit Pro Sound not working

Hi, we’ve had the Nanit pro camera on a floor stand for a few months now and for the first month or so the sound worked but I can’t get it to work now (receiving sound and this includes receiving notifications for sound).

I have tried; power cycling, resetting the network, hard resetting the device, and reinstalling the app and nothing - hoping this forum can help or will just look to return under warranty.