mortox 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.