I have been having issues with jobs that have Comcast X1 and a LG TV with HDR. On two jobs the ATV4K work after some fiddling but now is very consistent. The issue is after a while of ATV when you switch to the X1 the TV just turn to HDMI static, not sure what the technical name for this is. Most of the time if the TV is off for a while and then you turn on the X1 it is fine but if you go from ATV to X1 you get the full screen static. Sometimes you get no X1 video just static and sometimes you will be watching X1 for a while and then the static kicks in.

Not ideal.