Hi @ravven @magicman, thanks for your feedback. When tracking is disabled via the Game Hub, in fact the tracker itself has not been disabled rather the game is no longer taking gaze data. This is by design as it allows other applications that may be using gaze data (such as Windows Interaction) to continue to operate.
To completely disable eye tracking (and hence turn off the LED) the only current option is to disable eye tracking via the Tobii Interaction Icon in the Windows System tray.
However, depending on the game running, after eye tracking has been disabled, it may not operate again until the game is restarted.