Welcome to the club, this happens to me 3 times in 7 years. First, just a nick to the lift gate glass, second time, the garage door was damaged, third times , just two weeks ago, the lift gate glass was cracked and the garage door also slightly damaged. I permanently disabled the auto feature. In each instance, it is because the mechanism is a dumb toggle, if it didn’t open when I returned home and I manually open it, then not sure if it is a delay or what, it sends a signal which closes the .