Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Evidence does point to the LG CX having a problem with DolbyVision and associated audio. It looks like LG is working on it.
I also had a problem with audio from my SONY blu-ray. When I chose the blu-ray disc's DolbyVision 5.1 LPCM audio option, I didn't get any sound. Switched to the DolbyVision 2.0 LPCM option and I got sound.
The most recent LG update was applied last night and now I can get 5.1 LPCM sound from the blu-ray.
I have no intention of returning the Roku. As a software engineer myself I realize there are always certain kinks that have to be worked out and I am sure the fine folks at Roku and/or LG will figure out an appropriate fix. I did figure out that if I changed the sound from automatic detection to Dolby Digital Plus, I can watch the YouTube content without studder. It's just a matter of time.
Worse case scenario I will purchase another https://hdfury.com/product/4k-arcana-18gbps/ and put that in the mix. I have this on my LG C8 TV because it does not support eARC and appears to work well bit now that I think about it I am not sure I have tested it against sound coming out of Prime channel. Will test and report back.