I had a similar problem with my C9 and Fios one box . I replaced both devices and the issue was resolved . I would have Verizon replace the box . I had some other issues with the C9 so that was replaced . My Directv and Tivo boxes never had any problems with the LG OLED tv .I’m starting to believe it’s the new Fios TV one boxes that are the issue. I’m have the same no input detected problem on a Sony A9G. Also had it on my prior TVset after upgrading the Fios box.