I have an iPhone 8, and I almost never have a problem unlocking my Model 3 w/iPhone. However, occasionally, I see that my car doesn't lock when I walk away from the car after parking. I couldn't figure out why that was happening, but I think I figured it out. After parking the car, if I open the driver door while I still have my foot on the brake pedal, it seems the car stays powered on as if I'm still in the car ready to drive. For example, usually, when I park and open the door, headlights and the screen turn off. But if I park and open the door w/my foot on the brake, the headlights and the screen stay on and the car doesn't lock itself. Is this some sort of a feature? I guess you could use this feature if you need the headlights on while outside the car or if you want to keep the door unlocked (but then it'd drain the battery I assume?).