IK_foot_root doesn't follow the steps.

I found a tutorial that you can watch after that general one above that uses new features introduced in 5.1 to match your IK bones to your actual bones! You’ll have to bake a new animation, but this will walk you right through how to retarget the IK bones for your animation fast!

Disclaimer: This link is not associated with Epic Games, Unreal Engine, or their partners.