iPhone 11 streaming through appleTV

I have been using my iPhone 6S to show live feed through Apple TV. The feed is shown through a projector in my classroom. When I turned my phone on it’s side the live feed turned landscape and filled the screen. This was perfect for doing demonstrations to the class.

when I do the same using my new iPhone 11 the live stream will not switch into landscape mode on the projector. I don’t have the phone locked into portrait mode and I can’t find and other settings to change.

Any ideas?

Thanks