I got the 4.X update. Thought things were working smoothly, but not entirely.
If I set the Apple TV 4k to output DV/60, the screen image goes all pink and haywire. I can still see the content on screen, but it's entirely messed up.
If I set the Apple TV 4k to output HDR10/60, the screen goes black and doesn't come back.
The ATV can output 4k SDR/60 just fine. Also with match range and frame rate on, it will swap to DV/24 and HDR10/24 and everything works OK. I tried my Oppo 203. The menu comes up fine. Tried some HDR10 UHD disc ripped content and that played back OK too as the usual HDR10/24 auto switch.
I did some gaming on my Xbox One X, but it was just Crackdown via back compat, so that's just 4k SDR/60 but it played fine. I need to try the Xbox and my PS4 Pro at HDR/60 and see if things get messed up so I know it's an overall problem with HDR/60 or just the ATV.
Note the ATV is running the latest 11.3 OS off the beta path. I haven't actually tried DV/60 or HDR10/60 on the ATV any time recently, so I can't comment if it actually broke due to Apple or Vizio.
I haven't tried to cast anything yet using VUDU to see what I get.
Note all sources are passing through a Marantz AV7704 preamp then on to the TV using HDMI 1.
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