Firmware update has made my 4K TV a 1080p TV

I own a P50-C1. A couple of days ago, I came home and turned on my set to find that my Nvidia SHIELD was outputting at 1080p. I go into the settings and 1080p 60 is set as thedefault and recommended. I select 4k 30 and get a black screen.

I check my PS4 Pro and it's the same story: In my video settings, all 4K options are grayed out.

I switch from HDMI 1 to 2, 3, 4...Still 1080p. HDMI 5 gives me 4k, but not HDR.

I power cycle all my devices (unplugging power and HDMI from both ends for 30 seconds), which doesn't work. Finally, I plug my SHIELD directly into the TV, and that fixes it...Although the colors are just horrible. I had a preset that gave me the best quality I could get out of the set, and now that preset looks atrocious. I'm still fiddling with the sliders and it's taking me forever to get it back to its former glory.

The bigger problem is that my receiver is now suddenly unable to pass through 4k HDR, even though it was doing this fine at the beginning of the week. I suspect the 3.4.8.5 update messed something up, but I'm not sure what. I'm hitting Vizio support on multiple fronts (twitter, email and reddit), and I sincerely hope I get a solution to this issue. In the meantime, if anyone else is experiencing this issue and has any advice, hit me up.