Casting to Google TV with Chromeast (Answer for issue)

This is not really a question but seen many people ask this question and never seen an answer to it. I had the same issue that Xfinity Stream app will all of a sudden stop casting to Google TV with Chromecast. I finally found out today for some odd reason, my TV was the issue. The port I had the dongle on changed to 720p and I noticed in no place I could find to change it to any resolution on TV and the one on Google TV vanished too. I switched ports and got it to show the settings correctly in settings and was 1080p and casting worked again but that one port on TV stayed 720p. Its an older TV and had no settings to manually changing it so I factory reset my TV and now it all works correctly. I know its a TV issue now but why does Xfinity TV not let you cast to a TV on 720p? So all in all after three days searching and trying everything, even chat with support, I figured it out myself.