We recently got a 4K Xfinity STB and the picture is awesome. However, it dims randomly. Sometimes when we first turn it on, sometimes during viewing. Putting it into HD mode solves that issue. I've exhausted my support with Comcast as they think it's an issue with the Samsung TV. As others have reported issues with HDR and this class of TV I was wondering if anyone has come up with a workaround. I have ensured the TV does not have power saver on, as that caused issues in the past with UHD content.
I'm sorry to hear that, does this occur with every show you watch or with just HDR support shows?
It's so random, I have no idea. Why can't we just turn HDR off on the TV? People with these TVs are turning HDR off on their devices to stop this problem. There is no such ability on the X-1 box. We'll be watching a show (well did until I downgraded to standard HD) and it'll go dim. Two things fixed it, fully depower and reboot the TV or go to settings on the X1 and pick 30 or 60 fps and it goes back to bright.
So for a week or so we're just at standard HD.