I can think of a few things. 1: Does the Samsung TV need to be set to 'Extend Mode' on the HDMI input you're using? 2: Have you changed the 4K Mode of the AVR to '4K Mode 1'? You do this via the advanced menu that you would also use to access the factory initialization. This allows 18Gbps per second to be passed through. 3: Have you swapped HDMI cables? One of the cables may be missing the bandwidth required to enable pass through. 4: Have you checked the ATV's settings? What are the video outputs? 8 bit 4:2:0?
Also... run a backup via the IP setup of the AVR, then perform a factory reset.
This industry is not getting cheaper and cheaper, we're simply convincing ourselves that we have to push the cheapest option to customers. #makesonosgreatagain
