When switching to XFinity Flex (via HDMI), Screen Flashes Green and Black and then Low Resolution, Low Dimension XFinity Appears
When I switch the input of my TV to the HDMI connection associated with my XFinity Flex box, the TV screen flashes a green and black pattern. After a brief moment, the XFinity display appears, but it is scaled down and low resolution. The rest of the inputs to the TV work fine, including the built-in Roku. This is a new development -- it's worked fine for about a year.