Limb IK streches the foot when moving the body down?

Hi!

Maybe I'm just missing something super obvious but I can't seem to solve this issue:

I have limb IK turned on and everythign works fine when dragging the foot around via the heel control. However when moving the body down I run into this issue of the foot streching. It happens on both feet but not the arms. See attached images

I've followed along the Limb IK okaysamuari tutorial of having the frontal group etc. What's going wrong here?