I had an issue with my Tivo v6 box, an engineer has been out and solved my issue but now I am not getting a 4k output from my box..I've checked hdmi cables, swapped cables and swapped hdmi ports on my TV.
HD is fine. Using a high speed hdmi cable, didn't have any issue with 4k output before I had an issue with the v6 box. Just get a blank black screen if I select 2160 output. No 4k output on netflix or prime. TV only showing 1280. Firestick is outputting hdr to TV, so not a TV issue