No Sound from Nanit

Hello -

We currently have two Nanits, one for each of our babies. They have been working fine for quite a while. Our kids are in the same room so we generally listen through the one with the better sound, as we can hear both kids that way. But I noticed a few days ago that I am not getting any sound from the second Nanit. I've checked settings and everything is properly set, and frankly hasn't changed from when it was working. The video is working fine. The microphone works. But absolutely no sound is coming through the Nanit. Any ideas on how to troubleshoot this and/or anyone else had the same problem.

FWIW - I'm not talking about background audio. I'm talking about audio on when you are actively in the app (although background audio doesn't work either)

Thank you!