what power option is blocked? do you mean screen auto-off is not functioning again or LED power saving mode in mystic light settings disabled?So MSI Center is playing up again. Mystic light will turn off but the power saving options are blocked again.
are you waking the system from sleep\hibernate or power off?Additionally I have to go to Mystic Light and make a change to have lighting return.
by extended time do you mean an hour after the monitor automatically turned off. do you see LEDKeeper2.exe in task manager\details when the mystic light is not controlling the LED?If I leave my PC for an extended time the screen is still on but the lighting controlled by MSI Center and Mystic light are off.