Feet Not On Ground (Mechanim)

I'm using Mechanim and Pathfinding to move enemies. However, the feet don't stay on the ground. The wizard character starts above ground and the skeleton right on the ground, but once the game starts playing the wizard moves to right at the ground while the skeleton moves down a bit, just below the ground, and when the wizard gets close to the player camera, it starts drifting higher and ends up floating.

This happens with and without a rigidbody.

Any idea why this is happening or how to fix it?