[Note: I am having a very similar problem as the user who posted under the same Subject name but the Comcast employee (ComcastShane) took the thread private so I do not know if any solution was found.]
I have recently switched to Comcast. My receiver is my switch for all HDMI media so the X1 (like all my other devices) is hooked to my receiver. The problem occurs when I shut down my system (my remote shuts down the TV, receiver, and presumably the X1 although it is hard to tell since there is no discernable change in the X1 appearance) and then I later come back to watch TV and turn everything back on. The TV is either blank or frequently says no HDMI sgnal. The receiver and the TV are all on the correct HMDI inputs. All my other HDMI devcies (blu-ray, AppleTV, XBox) work fine when I follow this same process and the picture is there shortly aftering turning them on.
To answer a question asked in the similar thread -- the blue power light on the X1 stays on. In fact, the green activity light will flash anytime I press buttons on the DVR remote, as if it still works. Just nothing on the TV.
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