I have a strange scenario - or maybe not that strange. I have an Atmos AVR connected. When I play an Atmos disk, the disk player defaults to 5.1 sound. I always have to go into the disk menu to switch to Atmos. Any idea why this would be? Should there not be some communication with the AVR to tell the player to output best possible format?
Model of AVR? Name of title (or titles). What you are thinking about applies to video resolution and HDMI handshakes.
Generally speaking, things like languages/subtitles are typically driven by player/disc defaults. The only time I have seen similar situations is when a disc is authored to default to a certain soundtrack/config.