I’ve found a temporary fix from a reddit thread. Just add these nodes in the CR_Mannequin_BasicFootIK
This is definitely a temporary fix however as it seems to force the ik bones into position, regardless of the animation. I lack the knowledge though to find a proper fix but it seems that possibly the IK bones on the full body control rig don’t map properly to the default skeleton ik bones resulting in animations made or adjusted with the control rig lack IK movement.
To me it seemed all the right bone names were there in the control rig for at least the “Forward Legs / Feet” section but I could easily be wrong.