Unplugged my preamp from power and hdmi to the tv while went and visited family yesterday. Plugged it back in last night. DV/60 and HDR10/60 from the ATV both worked properly on my P75 again with the 4.x firmware.
Now to see if it still works tonight and try out the Xbox and PS4 in HDR/60 content.
Video: JVC NX7, Stewart Cima Neve 135"
Audio: Marantz AV7704, Emotiva XPA-11 Gen 3
Speakers: Focal Electra 1038 Be x 2, Electra CC 1008 Be, Aria 906 x 8, REL S5 SHO x 2
Sources: Apple TV 4k, Kaleidescape Strato, Xbox One X, Nintendo Switch
Xbox Live: TrackZ