@TazmanUK37 for your issue I would disconnect all HDMI devices and then hold the power button on the TV until the screen goes dark and then Samsung smart TV will come up and you can let go and then plug everything back in while it's on and it should rediscover your devices. I know that sometimes the link between devices is lost. We have this issue with our TV box. It used to work and it doesn't anymore. So try that and let me know.
@Badluck I would say it could be the hardware in each TV. I have 2 Mu7000's. I know the 6000 series is the lower teir tv's and I've heard that it's not just a different panel but some of the hardware is different as well. A lot of people complain about the lower end tv's having issue with their panels and apps being wonky from time to time. Try reseting your TV and settings and get it back to where you want it and see if it makes a difference. I'm sorry I haven't been much help on this issue.
I have been getting "green flashes" (and occasionally pink and white) with my Nvidia Shield TV. My HDMI cables are high speed with ethernet (2.0 I think), have done a hard reset on both my Shiled TV and MU6470. It got a bit better with 1260 but still getting green flashes.
I really hope 1262 fixes this very annoying problem.
PS On the plus side the hard reset sorted my samsung remote -I can now control my Shiled TV with it.
@vangeliis the 1262 didn't work for me the only difference for me was on the firestick where the green flashes are now now white flashes instead. but the PS4 still gets green flashes if u switch the hdmi to pc mode that seems to stop the flashes