Unity – Root Motion Physic Material Issue

I have a slope with an "icy" physic material with 0 static and dynamic friction. I also have this same physic material set to my model’s capsule collider. The model’s rigid body has a mass of 10.

When the penguin preforms its root motion belly slide on the ice, I expect the physics engine to do its work and see the penguin slide down the slope. However, I instead see a slow, sort of inching down the slope as shown in linked video. When I turn root motion off, the sliding works as expected.

What is going on here? What about root motion would be causing this?

I have tried a slew of root transform position baking options (including y) and it seems none make any difference.

Any insight is much appreciated! Thanks.