Problem with remote back button controlling Apple TV
I have a Bravia 9 ii with an Apple TV 4K connected. All was working fine but suddenly the back button on the Sony remote will not work for the Apple TV. All the other buttons work, and the back button works for the Bravia itself and for an Nvidia Shield that's also connected. I've tried power cycles, disconnecting and reconnecting the devices. Also disabling then enabling HDMI-CEC but nothing clears the problem. Has anyone else seen this and managed to fix it? The problem exists for both the remotes that came with the Bravia.