FB animation in VR using PowerIK

I’m developing a full body IK system for VR using HMD and controllers only.

I have a working solution using FABRIK and PowerIK ground node.

VR_arms_IK_using_FABRIK.gif

However, the arms movement is glitchy and I’d rather use PowerIK for the arms.

VR_arms_IK_using_PowerIK

However, when I try to do so, the arms IK affects the hips transform. This in turn moves the feet around. I have tried adjusting every relevant setting to stop this, but am unable.
I have tried zeroing the Pull Factors and Pull Weights on the hand effectors. ‘Affects Center of Gravity’ is unchecked. I have even tried setting the root bone to spine_1 (this will crash UE every time btw!)

I am out of ideas as to how to stop PowerIK affecting the hips. Any guidance would be gratefully received.

~ davedub