With HDMI connectivity, it's two-way communication throughout your HDMI connected system. You might have a problem with any of your HDMI connected devices. I would suggest disconnecting all the input HDMI cables and see if you still have the problem with only your 4k cable going to the TV. If it works then, connect one input device at a time to see if either of them are causing interruption. Have you tried cleaning the cable ends with a cleaner solution? That might help if one cable works while the other does not.