All of a sudden the Cable Box "app" located 1st app to the right of HOME has stopped working. Clicking on it does not bring up my cable (Xfinity X1). It worked fine for the last 6 months on my Sharp ROKU TV and just stopped working. Clicking on the app does nothing. I had Xfinity recycle everything but it didn't fix the problem. The cable is connected to the HDMI1 input (ARC). I can still get to the cable by going to Settings-> TV Picture Settings -> Settings per input -> Xfinity X1. Very strange.
Welcome to the Roku Community and thanks for posting regarding your input tiles on your Roku TV.
Have you tried checking to see what your tiles are currently set to? Try accessing your TV inputs by going to Settings > TV inputs > Cable box and making sure that the HDMI 1 (ARC) is showing when you select the Cable box.
Please keep us posted what you find out and we will be able to assist you further.
Mine started doing this today. It worked fine this morning but this evening it is not working. I can get to my cable box by going to TV picture settings --> cable box but that is a hassle. Did you unplug the tv or cable box?