NTEK IR told me that some of the Paramount uploads are only streaming in High Quality "HD" right now for some of the TV models like our SAMSUNG, But they are working on UPSCALING them ALL to full 4K and should be finished in about a week.
It depends on the movie though. For example SPONGE BOB streams FANTASTIC in the highest 4K mbs setting. Looks AWESOME.
But other movies we can only stream in "HD" mode for right now.
I can only tell you what is happening with us and how D Wong explained it.
Not all, but some of the new Paramounts on our SAMSUNG can only be streamed in the "HD" mode. anything in the 4K mode of 4MbS or higher they stutter. By the way Even in ULTRAFLIX "HD" mode they still look better than anything Netflix has in "HD".
DWong explained to me NTEK is aware of this issue for our model SAMSUNG and they are working with SAMSUNG to UPSCALE these films to 4K streaming capable and should have them all complete in about a week.
I don't know if others are having this issue on other model TVs or not so I'm just relaying this experience.