Airplay to multiple Apple TV's?

Hi,

I have tested this from a MacBook Pro on macOS Venutra to 2x Apple TV"s and had success.

On my second attempt, I can't seem to get it two work. I remember you have to hold option + click the Apple TV's in the Airplay list. I definitely saw it work.

Is there a trick and is there a limit of how many Apple Tv's you can Airplay to?

Thanks