I received the update yesterday, but the notes show only Dog Mode and Self-Folding Mirror option, no Sentry Mode. I can see the toggle switch on my phone app, and when I select it, the car display has a big red HAL eye, with the message that it is recording. However, no amount of arm-flapping and hovering will trigger an alarm.
BTW, I love the auto-activated mirror fold. It was one of my first "wish list" items!