I've been having trouble getting auto game mode to work with my xbox one x. When I first unboxed the TV and went through the setup guide it automatically recognised the xbox as a games console and automatically switched to game mode when I loaded a game up. After tweaking some settings (can't remember which exactly) auto game mode on the tv is now greyed out. I reset the TV again the other day and the function worked again but then after changing some picture settings it no longer works!
TV is a nu7500
I never found a permanent solution. Only way to get it working was to factory reset the TV! But then as soon as you change a few settings on the TV (still not sure which settings) the option is no longer available.
Was hoping it was more widespread tbh as can't find anything online.