I've downloaded an FBX animation of someone walking from the "Walking" section here.
I imported that and also a humanoid character and specified the Rig for both as Humanoid (auto-create).
The original animation has very solid foot placement, but whenever I apply it to any character in Unity the feet slide around as if it were walking on ice.
Here is a video demonstrating my issue. Is there something about the way I am getting Unity to auto-rig my character that would cause this problem? It happens no matter which 3D character I use.