I finally, FINALLY fixed my flicker in 4k RGB. It was the right set of HDMI cables.
For the past year I suffered with about 5 picture resets during a roughly of 2 hours per gaming session. Usually the cutoffs happened during the first 20 minutes, but happened randomly after that.
My ps4 is connected to a Onkyo receiver, from there to the smart box.
I tried different cables without avail. Until I finally found the cables that worked, Clas Ohlson 1.5m HDMI 2.0 graded cables.
I've now gamed for about 2 months without a single cutoff in picture.
It really is the cables, even though I was 100% sure there is handshake issue between the tv and ps4 pro. Note that I switched both the ps4-onkyo and onkyo-smart box cables. I had the original hdmi cable that came with my ps4 pro.