Thank you for bringing up the concern you're experiencing, I would love to look into this further for you. The first troubleshooting step that I'd recommend would be to restart your device. This process should keep all your settings, and reconnect it to the same Wi-Fi network. This is helpful if it ever freezes, has connection problems, or isn't working normally.
@kh7 aside from restarting your device, you may try going to the settings of your iPhone and look for your Nest app or Google Home app. Go to permissions or notifications and make sure your audio is enabled. Looking forward to your response.
I appreciate the help, Brad.