its 100% cale related. When i went to a good cable[still under 10 dollars] problem went away. have never had it sinceI just got my PS4 Pro and after a week of use, I have never encountered the black screen flicker problem yet. I used the same HDMI cable I used with my old PS4 (since I know that one works well with HDR) and use Auto (which does send a 4:2:2 signal) together with my KS9000.
Could the problem just really be cable related, because I actually have 1 or 2 cables that do exhibit issues with HDR and/or deep color.