Just got the new Ultra and set it up to play on my Sony XBR-65A9G Master OLED through a Sony STR-DN1080 receiver.
I am unable to get 4k and Dolby Vision simultaneously from the ROKU. The unit will configure 4k/60p without Dolby Vision or it will configure Dolby Vision at 1080p only.
I know the TV can support the 4k + DV combination because my Ultra HD player feeds it as does my Fire TV 4k.
What am I missing here?
So here is the issue:
I was feeding the ROKU signal through the HDMI jack on the AVR labeled "VIDEO1". Turns out that is the only port that doesn't support anything beyond 9gb bandwidth! DOH!
Plugging into any of the other jacks works just fine!
(This is indeed documented in the Sony docs, if you get that far.)
I have zero experience with Dolby Vision. The LG set I just bought does support it, but my AVR doesn't. From what I've heard from other posters on other forums, DV can be touchy with some Sony products, although I believe that was mostly devices that were from 2017 or before. Both of yours appear to be more recent, so I wouldn't expect them to have issues.
It's possible your HDMI cable isn't satisfying the bandwidth requirement for 4K/60 HDR. It has to be a certified 18 Gbps cable to support that requirement. So that's the first thing I'd try. That tripped me up when I replaced my Roku 4 with the original Ultra. My cable worked fine on the 4, but would not work with the Ultra at 4K/60.
I specifically wired it with a 48 gig wire!
It is part of a 3-pack., one of which is doing the 4k/dv to the disc player. But as a double-check, I can swap the wires.
What's worse is that if I force the ROKU to 4K without DV, the next time I turn it on, it reverts to 1080p with DV. I can set it back each time I turn it on, but that's just on the borderline of unusability.
Same here with my 2016 LG OLED E65. All LG OLED's prior to 2018 or 2017 only supported Dolby Vision 4K at 30hz. The Roku Ultra 4800R is forcing me to Dolby Vision at 1080p/60hz, and the picture is worse than regular 4K. I have set mine manually to 4K/60hz and not sure if it's resetting back to DV though. I do wish that they would just quickly fix Dolby Vision to support 4K at 30hz, which is still better than HDR10 for movies, etc.
While I of course don't have the new Ultra, my current Ultras allow setting the display at 4K/30. Is that not available on the 4800, at least with the displays you're using?
It will recognize my 4K/60 and allow me to set it, but then it resets it the next time I turn it on to 1080p/DV.
I can change the TV to something other than DV, but the picture is noticeably not as good and as I posted earlier, Fire TV doesn't have this issue.
Sounds like they have some fine tuning for DV that will have to be done.