I forced a manual update and the issue seems to be fixed on my TCL 75R617 (Roku model 7138X). Stats for Nerds shows buffering between about 7 - 25 seconds and no stuttering or pausing every couple of seconds. And the app stays in 2160p instead of downshifting to 1440 or 1080. Thanks for the fix.
Cyberbytli, that video does cause stuttering/pausing on my TV, I guess because it's 60 fps. Buffering is only about 2 seconds. I checked some other 4k/60 videos and they do the same. Anything at 24 or 30 fps plays fine now.
I also have a Windows desktop PC connected to this TV as a source, and it has always played all 4K videos on YT smoothly, usually buffering around 25 seconds, but with the 3840x2160@60 videos, even it drops down to about :07 of buffering.
Here is the info you last requested concerning Issue reports. There are two, along with some pics with the Stats for Nerds screen shots. You can see how the buffering health goes to 0 seconds, which results in freezing of video and sound. It will then sometimes pick back up when buffer goes above 2s, only to drop again soon after. If It will down grade to 1440/60 or lower if in auto mode. If manually selecting 2160/60 it will not play that resolution reliably for more than a minute. After down loading the latest Roku OS update manually, it seemed to have fixed the problem, but it did not last long.
Also notice the photo taken of my 75R655, which shows a much higher speed, with sufficient buffering. It does not have the problem, yet. Same network. Both TVs typically show speeds on the Roku network of 80 Mbps to 116Mbps. Keep in mind, if using a Fire TV 4k stick or other apps. 4k content plays fine. The problen is only on YouTube or YoutubeTV.
Same problem is happening for me. I am trying to access 4K content from Plex server. It keeps buffering in every 2-3 seconds, eventually is getting stopped. Mine is RCA 43" 4K SMRT, Model Number: RTRU4328