NonKinematic Rigidbody moved with Rigidbody.MovePosition not interacting with other NonKinematic Rigidbody as expected.

I have a disc that is controlled by user input and Rigidbody.MovePosition. It has a Rigidbody component. I also have a sphere with a Rigidbody component. They are both locked into the X-Y plane and neither use gravity (so a side on view, no gravity). When neither of the objects have Is Kinematic set to true, when the user moves the disc into the sphere it simply pushes the sphere out of the way and the sphere stops, as if they can't occupy the same space and that's it. I expected it to hit the sphere and cause the sphere to go flying. When I set the disc's Is Kinematic property to true, it behaves as expected and knocks the sphere around. What is causing this? Thank you!