Apple TV display multiple homekit cameras

I have three Homekit cameras and an Apple TV box used as a hub.

On the Apple TV screen I can display two of three camera images side by side, but can't find a way to get all three to display at once.

The 'tile' icon shows a 2x2 array which suggests that it should be possible to display these in a grid, but all I can get is two of the images side by side.

All the cameras are working fine, and allocated to rooms.