I have the latest Apple TV 4K. It is connected via ethernet and via HDMI to my Denon AVR-6800 receiver. When watching a source broadcasting in 2 channel, it will not allow me to upscale using Dolby Surround. Even through the receiver shows 5 channels playing when choosing Dolby Surround, only the left and right speaker are outputting sound. I also have a Google Chromecast and a Roku Ultra. Both of these will allow outputting 5 channels from a 2 channel source. And all 5 channels are playing. The Apple TV will not. I have spoken with Apple CS and a senior advisor. And they are stumped. Has anyone experienced something similar and if so, is there a fix.
My Apple TV is running tvOS 26.6 (23L773).