"Flat Collision" - Ball is sliding on wall, not bouncing off

Hi there, a physics question here.

Instead of bouncing off of a wall like it should be, the sphere is “sliding” on it after a collision. Better yet, watch this video to see what I’m talking about. What is going on? How do I fix it?

Video: flatCollisionsiOS

Thanks for your help.

Edit → Project Settings → Physics → Bounce Threshold