For several months now, I've had our Apple TV 4K streaming audio to the older 3rd gen device and then out to our surround sound system. Since Saturday, Feb 9 this no longer works. I used to choose the 3rd gen as an audio output source. It no longer appears there. Both devices are on the same network, and are connected to the same iCloud account. Bluetooth is working on both devices. Sound is working on the 3rd gen. But the 4K does not recognize the 3rd gen. Any ideas on how to get this working again?