My TCL 55R625 has support for Auto Game Mode, and I've confirmed that the feature works via my Xbox. I've toggled on the "Automatically turn on game mode" option in the Google Home app, but the TV will not switch to Game Mode when playing Stadia. I have to manually enable it each time. Has anyone else experienced this issue with TCL TVs? If so, have you found a fix? Thanks!
My TV doesn't support it (Sony XBR65X900E, 2017 model) but it has a feature to automatically change to game mode based on the display mode which works fine. Do you have an option like this you might be able to use? Apart from that do you have the CCU connected directly to the TV or through some other equipment? If connected through something else it's very likely passing through it is killing off the feature as everything in the chain needs to know what to do with it. If it is connected directly to the TV, it's not uncommon for certain HDMI ports on TV to be gimped and not offer the full set of features - try switching places between your xbox that it works on and the CCU in terms of cables/inputs and see if anything changes.