XG1v4 Streaming 4K Causes Pixelation

@bvwhitney​  what is the brand of the cable that works for you and where did you buy it?   What is the rating on the cable?  8K, 4K, lower?  Are you sure you are watching the content in 4K mode with the cable that works?   If I step down my TV to regular HD instead of selecting 4K, the pixelation problem goes away but so does the great 4K picture detail.  That defeats the purpose of having a 4K TV.  

I wish I knew the brand of cable that is working, but there are no markings on the cable to identify the manufacturer.  I have a box of about 20 HDMI cables, and I just started testing to find one that would work.  All cables I tested work fine at FHD and HD, but until I found the one that worked, I would get sparkles in my screen on 4K video sources.  I am certain I was using 4K sources, via streaming from the DVR.  I have Xfinity as my cable company only offers HD video (720P) except for a few local channels that are FHD (1080I).  I can stream the few available 4K videos on Netflix (premium member) and Amazon from my Tivo without problems.  

I recently purchased a Netflix Premium subscription.  I get no pixelation whatsoever streaming 4K Netflix through the DVR.  I have only found the pixelation to occur with a combination of certain Amazon 4K content streaming through the DVR but not all 4K content.  I wonder if the creation of 4K content can vary in quality or process which causes the issue in some 4K versions.  If you have an Amazon Prime subscription, try streaming Bosch UHD 4K through the DVR.  Scan for dark scenes then look near the top of the image slightly to the left of center.  I get at least 30 specs of white flicking light sometimes moving around and sometimes fixed in one position on the screen.  Please let me know what happens.