On two separate Roku Ultras (4800X 2020 model), I have noticed the same thing. Out of the box, the units update to 9.4 software. With the 9.4 software, they worked flawlessly on my setup, which upscales all content to Dolby Vision, then routes over high speed HDMI cables through a Denon Receiver (high end 2020 model) to a LG CX OLED (also 2020 model).
After about a week of flawless operation on the 9.4 software the Rokus decide they need to update to 10.0.0 software. After that update, the screen will flash to complete black every 5-20 minutes or so. Audio continues to play during the black screen. It stays black for a few seconds, and then comes back on. When it comes back, the TV shows the Dolby Vision logo indicating a fresh signal handshake.
Things that did not help:
* Trying different HDMI cables (I am using 48GB certified cables, but I tried other cables as well).
* Enabling passthrough mode for the video signal in the receiver
* Trying different HDMI ports on the receiver and TV
* Forcing display settings to HDR instead of using auto-detect
* Turning off pure black in the TV settings
I also tried connecting directly to the TV. With this setup, I did not notice any flashes to black, but I did not leave it connected like this for too long, since routing the audio back out of the TV to a receiver introduces a very noticeable AV sync problem (LG TVs are pretty notorious for this). So this isn't really a viable config option for my system.
It would really be a shame to have to turn off Dolby Vision on the Roku, since the picture quality is spectacular on this setup when it is working. Any ideas?
Not sure that "upscaling" best describes SDR/HDR10/HLG content being packaged in DV, by most standards, since it results in an improperly mapped colorspace amongst other issues.
Regardless, it sounds like you have "HDR always on" enabled (Settings/System/Advanced system settings/Advanced display settings) - is there some reason for this? I highly recommend disabling it, so that content is output in the relevant correct colorspace per the actual content, etc.
Also, what build of 10.0.0 do you have? The latest build (4177) allows manually configuring 4K DV or 4K HDR10 separately, so you might want to try each.
Also, as it happens, the occasional sporadic "black flashing" has been reported by others with 4177, so you should report this directly to Roku:
chat or email: https://support.roku.com/contactus/contact-options (setup/ultra/other/need more help?)
It's very helpful to know that others could be having similar issues with this software build (I am also on build 4177). I did open a support ticket as well, so we will see where that goes. I may also try limiting the output to HDR10 to see if that behaves any better.
I see this issue across all channels, including those that output true DV content. Thus, I am not super optimistic that disabling HDR always on will help (though it may reduce the surface area of the problem by limiting it to just DV-capable channels). For completeness, one main reason I have not disabled HDR always on is that I have not been able to recreate the same quality of picture on my OLED TV when it is receiving non-HDR content. The TV picture mode settings change based on HDR vs regular input, and I have not yet been able to tweak the non-HDR settings to have movies show up as well as they do with HDR. This is very much a me problem as my TV+receiver+Roku setup is a fairly recent upgrade.
I have the same issue, *exactly* as described. Started with SW 10.0.0 build 4177. I have a Roku ultra with LG OLED TV with a Yamaha receiver with video pass thru.
I reported to customer service
Any way to revert to previous SW?
Can confirm that I started noticing the same thing after the update to the 10.0 software. Using a Roku Ultra and an LG OLED55BXPUA TV
I too have the same problem since s/w upgrade to 10. Roku ultra 4800, LG OLED and Marantz SR6012. Blackouts went away with disabling HDR Always on but picture quality seems compromised by comparison.
I too am having the same problem with my LG C9 OLED and Denon receiver. Even after I try and change the settings on the Roku to just 4K HDR, the device will then revert to Auto Detect for the display settings. I have noticed that on some apps it happens way more than others. I know it happens quite a bit with Discovery +
It seems a bit of a coincidence that this is happening with one specific brand/model of TV. I too have an LG, but it's not the OLED version. I haven't seen any flashes using Disney+ or HBO Max. I'll absolutely keep watching for it.
I suggest that the HDR Always should never be left on. I have no idea why Roku has it as a default setting, as it's altering the incoming video signal, and it's really not capable of synthesizing HDR from non-HDR content. Any perceived improvement in video quality simply isn't an accurate picture.
Unless your AVR has some super high quality processing onboard, you should always your AVR set to video passthrough. If any video processing needs to be done, your TV will likely do it far better than your AVR.