We set all displays and Apple TVs to RGB. That stabilized things a little especially on the stand alone sets. But the real kicker came in when I set the Marantz receivers to "enhanced" from "standard" 4K. The reason I had not done this before was that the receiver in both rooms was telling me something was wrong with the cables so it would not work so I didn't accept because I really did not want to have to factory default units. Out of frustration I forced "enhanced" on both units and walla...no more flickering, no more blackouts, minimal sync issues, etc etc etc.
I turns out I was attempting to lower the resolution to make it easier on the system but the Apple TV was forcing its higher resolution so I needed to force the system to perform rather that step things down. In some ways opposite of what we have been taught over the years with HDMI.
HOWEVER....The system is still largely inoperable. About 50 percent of the time on Netflix and maybe 20 percent of the time on Hulu, when we play anything the screen just shows green or black. We can still see the network logo in the corner and the Apple TV subtitle screen pulls down, navigation bar is shown but any content is just a green or black screen. Not a little washed out like the purple screen we have all seen but a solid green image.
