Hi, there is a lot of posts on foruns showing that 4k 120Hz is now activate in HDMI 4 of this tv. Can you confirm this?
When you play HDR content many settings change to what they were the last time you were playing HDR content, and the backlight for HDR content is max by default. Also settings you changed while HDR content was not playing may not be applied for HDR content, which is why we recommend playing HDR content before changing settings to our recommended HDR gaming settings. There is a bug though that when you are in game mode and playing HDR content over HDMI the backlight will not change to max automatically, it'll remain at what it was before; in that case you may need to change it manually.