Hello!

I am the owner of a "65 A1 TV and an Apple TV 4K and am experiencing some issues. I hoped that someone would have a tip for me, or let me know that I am not alone in this.

When woken after being on standby for a certain period  (could be one hour or more), the TV will not detect any signal over the HDMI port (HDMI 2) to which the Apple TV 4K is connected. The screen would flash slightly, in what appears to be an attempt at establishing a handshake, but that attempt will ultimately fail. 

When the above occurs, the HDMI input in question becomes unstable even when connected with other devices (for instance, connecting a PS4 Pro will result in unstable image). Subsequently, the only way to regain proper connectivity on that particular HDMI port is to power cycle the TV itself (not the Apple TV). After the TV is power cycled, everything works properly again. By power cycling, I mean soft-restart ("About" -> "Restart") as well.

Playing with CEC-related settings on the Apple TV appears to significantly affect the incidence of this issue, but will not eliminate it outright. Moreover, disabling Enhanced HDMI on the TV eliminates this issue, but at the cost of HDR support – which is significant.

Both devices are updated to their latest respective software releases. There appears to be some state corruption that is occurring during standby (applicable to Enhanced HDMI mode), which clears after the TV is power cycled.

Did anyone experience anything similar?

Thanks!

P.S. Could anyone explain what exactly happens with the HDMI ports or controllers during a power cycle or a soft-restart?