So I recently invested in the LG OLED55C7P, which is gorgeous. I can now run my individual HDMI sources (Cable, Apple TV 4K, Xbox One X) to the TV, and audio out through optical to the playbar and beyond. All was good for video and sound - 5.1 for each source, and I didn't need a splitter (I used the Octava before, with my old TV).
In reading about Dolby Vision, etc., I saw that Apple recommended the Belkin Ultra High Speed HDMI cable. I saw conflicting opinions, but I wanted to use the best that I could, so I bought the cable and stuck it between the Apple TV and the TV. Boom - I started getting the 'Unsupported Audio' error in Sonos. I recycled power for everything, tweaked the TV audio output settings, tweaked the Apple TV audio output settings, and no luck. So, I swapped the good old HDMI cable back in, and life is fine.
So my question is - does anyone have perspective on why this cable, which I'd assume would be backward compatible, would have issues? The TV (2017 model) can pass through Dolby Digital/DTS multichannel via Optical, and it works fine with the non-Belkin cable between the Apple TV and it. I'm still getting Dolby Vision via the Apple TV with the old cable, so I don't seem to have lost anything, but it didn't make sense to me, so I figured I'd ask the experts!
Thanks in advance for any thoughts.