Mecanim Floating Feet

I have a setup where the parent GO has a rigidbody + CC for the player controller. Underneath that, is the character w/Animator component. My problem is that in the idle animation, the character makes some movements that seem to drive the motion of the CC which is a parent node.

From what I've seen, joints, even as children, can affect the position of the entire GO even the parent nodes.

What I'd like to do is prevent the players feet from moving. If I drop a character + animator in the world it will work fine, they will go through the entire idle without any foot movement.

I've tried transform and body masking to no avail.

Is there some way to "disable" a rig from affecting the position/rotation of parent GO's in a hierarchy?

Seems to me this should be as easy as masking out the root node and therefore not getting motion from it, but that does nothing here.