Okay, I know I'm real late to this party, and I've done a fair amount of research due diligence on this thread, but I'm not experiencing what people have been saying about the inability to have both Dolby Vision and Dolby Atmos run at the same time, because I do.
4K Apple TV
4KATV HDMI-Out --> K950 HDM2-In
K950 HDMI-Out (TV-ARC) --> LG OLED HDMI2-In (ARC)
With this setup, I am able to fire-up content with both Dolby Vision and Dolby Atmos from the Netflix App on my ATV, and I do in fact get both Dolby Vision video and Dolby Atmos sound. How do I know? Because I've got the Apple developer HUD (via Xcode) up and running on the screen listing all the video specs in real time, one of which is clearly "Dolby Vision". I also know Atmos is working because the blue light on the side of the soundbar lights up.
I sent my soundbar back to Samsung a couple of months ago and they changed out the control board as well as the HDMI connections. Any chance I ended with updated versions of either? E.g. HDMI 2.0a?
Any thoughts? Thx!!