Question, I have an ATV 4K box latest gen with HDR10+ capability, I have a few movies in my iTunes library that offer HDR10+ but when I try to play them from my library it only plays in HDR10, The Thing digital copy for example, if I play it from watch now or continue watching in the ATV+ header it displays in HDR10+, anyone know why that happens?
Under Audio and Video Format settings are you seeing that HDR10+ is an available option.
If the ATV4K has recognised the TV is compatible It’ll show 4K HDR(HDR10+) as seen here
https://preview.redd.it/becf9ds7ax2c1.jpeg?width=640&format=pjpg&auto=webp&s=f0f2db124cfae76a3b04c16c12339a7a1b842e80
Of course HDR10+ is available, my OP stated it plays in HDR10+ when starting movie from continue watching, tags only HDR10 though when playing from my library.