Apple TV and Phantom I

[jacob]

With the same setup as above my Phantoms still appear in the Temp option list but not the Default option list.

Weirdness, nothing there either. 

I have this setup:

AppleTV (4k, newest tvOS) -> TV -> optical out  -> pair of silver phantoms.
This works fine. 
I can also choose to connect to the silvers directly from the AppleTV via Airplay. This also works fine.

airplay speakers to choose from, can come and go from apple devices, and it is usually network related.
Try to disconnect and reconnect to network from all involved, thus appleTV, Phantoms.
If this does not help, try restarting your router.
Sometimes routers block certain traffic and sometime between different network segments (if one is on wifi the other on lan) which can also hamper airplay.