Sorry if this isn't the right sub to ask this. I googled a ton and couldn't seem to find the exact same scenario, and I'm posting in a few related subs to find answers.
I have an LG CX, shield pro 2019, all running through a Sony STR-DH790 AVR, all connected with 48 Gbps HDMI 2.1 cables. The shield is on a very strong 5 Ghhz wifi band. I was watching The Witcher season 1 earlier today on the shield Netflix app, and DolbyVision engaged appropriately. I went away for a couple of hours, came back, started to watch season 2, and I'm no longer getting DV. I do get the "VISION-ATMOS" logo on the show screen in Netflix, but it just doesn't switch on now. Even going back to season 1 doesn't engage it.
By all accounts, I assume my configuration is correct since it was working earlier. I do have DV enabled on the shield, and my current resolution says "DolbyVision and HDR ready". My DV content on plex works correctly. So I'm not sure what's going on here. Any help is appreciated!
Long time shield with an avr and LG c8 user here, I've seen this happen on occasion. I think it's a handshake issue with in the HDMI chain, since it seems that Netflix checks for Dolby vision, Atmos, and HDR compatibility each time devices are powered on or off. Easiest way I've found to fix is force close the Netflix app (double tap home and then down on Netflix to force close) then just reopen the app with everything powered on. Whole system restart also works.