Context
I've been trying to bump my TCL 635's gamma. My living room is very bright and playing HDR games is pretty terrible when the sun is up. For some reason, the gamma setting is only accessible via the Roku app, but not on the TV itself, which is another discussion all on its own.
Issue
The Roku app does not have the "Gaming" or "HDR Gaming" picture modes. Only "HDR Bright", "HDR Normal" and "HDR Dark". The same goes for non-HDR modes. If you use your TV's remote to swap to the Gaming picture mode, the app will return "Operation Error." or simply crashes. You cannot access the settings until you swap to another picture mode.
Effectively, this means you simply cannot change the gamma for the HDR Gaming profile, which is exactly was I trying to achieve.
Many TVs lock certain settings when using specific profiles. Locking the gamma setting while in the gaming profile might be one of those cases. Hard to say if it's a Roku OS issue or something specific with TCL TVs. Since Roku doesn't manufacture the TVs, they provide the OS to the manufacturer, who might make alterations.