Getting in on this late, but I notice the refrigerator is at an oblique angle to the front of the car. That could definitely cause problems reflecting the ultrasonic sensor output.
Good thought rxlawdude. That could explain why my Model S stopped with about only 6" clearance even though distance is set to 16".
So then the mystery is why did it continue past that point and hit the fridge corner after I accidentally re-initiated summon with my key fob?