Apple TV casting with HDMI-CEC - why won't Airplay force source switch?

[4pp13]

I have a brand new Apple TV for Christmas. Hate that BBC hasn't sorted out the subtitles issues yet, but that's not Apple's problem so I'm willing to try to look past that given I want Fitness+ casting.

However on the Airplay casting feature, I can't seem to get Airplaying from phone to force a switch to the Apple TV HDMI source. This is with a HDMI-CEC connection, so I had expected this to work. It definitely works for Chromecast.

I don't really want to have to find the remote to switch the input AND THEN airplay if I don't have to. Does anyone know if Apple TV can do this? I have tried searching but not sure if this question is asked so often as I can't find similar. Is the expected result below actually possible? How do I make it happen?

Steps to repeat:
I've got an Apple TV on HDMI-CEC port 3.
I am watching something on another device hooked into HDMI-CEC port 1.
I decide actually I want to cast something from say Youtube.
I click the cast button in youtube to say Airplay to Apple TV.

Expected result:
TV automatically switches from HDMI-CEC port 1 to port 3 (the Apple TV port) and video plays

Actual result:
Apple remote has to be pressed to switch to the Apple TV source
The video to be casted can then be played

 

[waw74]

I click the cast button in youtube to say Airplay to Apple TV.

you need to make sure you click the "airplay and bluetooth devices", it's a button and not a title for the things shown under it.

if you click the appleTV that shows under that, you're sending from the YouTube app to the YouTube app
With the appleTV, for it to show up in that list, the YouTube app must be open on the appleTV, meaning not much happens on the appleTV to start playing, which is why nothing switches.
On other devices besides appleTV, they can show up without the app running on the device, especially chrome cast, since google has control over all the parts you're trying to use.

if you click "airplay and bluetooth devices" and then click "appleTV" in the new menu that shows up, then you're using airplay, and it should switch and power on everything automatically