I have been having the same issue as well. After going through the blueprints many times, I believe it comes down to the Effector Location and the Two Bone IK nodes (or FABRIK nodes). My theory is that when not moving, the IK Foot Trace is continuously outputting an effector location that’s moving forward relative to the character, and the FABRIK nodes are therefore continuously transforming the foot location forward.
I am still attempting to figure it out, but many thanks in advance if someone has the solution. 