Same issue. After update to 5.10.04, Apple TV playing Dolby Vision content to the C9 through my Denon 6300X receiver no longer works. Screen flashes black. Had to turn Dolby Vision off to resolve which is of course not ideal for an expensive OLED TV that you bought to use with Dolby Vision.
Hoping LG can push out an option to revert back to previous firmware which worked fine, or an update to this new firmware to fix the issue. It's ridiculous to not be able to watch Dolby Vision content on my OLED TV.
