This happened today at lunch. When I parked I pulled onto the parking bumper and heard it bottom out so I pulled back off of it. It didn't sound good but I've done this before so didn't think much of it. After lunch I drove back to work and parked and noticed it hanging loose there.
If you look at the pictures it has 3 clips which the screw fastens into. I lost all but the one screw and clip. Luckily with how the plastic teeth connect into the underside along with the one screw/clip it seems to be fastened well enough. As long as I don't pull back over a parking bumper again.
I'm planning to go back to the original parking lot tomorrow to see if I can find any screws and clips so I can fasten it correctly.
Anyway, this is a post to warn others about possibly doing the same and I hope it helps avoid similar issues.