I have found several issues suddenly arise from time to time with my Samsung QLED. Greyed out setting features, remote not paired, etc... I turn off the tv, unplug it from the outlet, then plug it back it. This works as a fix for many issues. It worked to reset the setting options so that all are available.
Some other settings were greyed out one our Samsung smart Tv. How i fixed it was that i put the tv in demo mode, and switched it back to personal mode. Then all the settings were selectable.