Gameobject won't bounce after colliding when velocity is exact 1

Hi, I have a very weird situation going on, in my 2D game I have a biscuit game object moving towards a wall, when the biscuit hit the wall, it's supposed to bounce back because the biscuit has a CircleCollider2D and the wall has an EdgeCollider2D attached, and biscuit has a RigidBody2D as well.

But the problem is, if I set the biscuit velocity greater than 1 ( 1.1, 1,2, 2.0...) , it will bounce back perfectly, but once it is set to exactly 1, it will suddenly not bounce at all! the biscuit just stick to the wall....

It's so weird I couldn't figure out why, I set both collider with physics material with Friction 0 and Bounciness 1, and it just won't give me any correct result (with or without physics material) .

Great thanks for any help!