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IK jitter/snapping?

I have a looping animation that involves leg IK in Maya (basically a squat and stand-up, repeating). My skeleton has extra joints parented to the Maya rig’s IK ankle and pole vector controls. When I import the animation, I can have UE4’s Two-Bone IK “take over” the IK solving by setting the effectors to follow those joints.

I can’t directly apply UE4 Two-Bone IK to the deformation skeleton, because it has twist joints. So instead, I created a setup that reads the positions of the Two-Bone IK bones and updates the deformation bones with the proper twist and bends.

The system works ok, EXCEPT for seemingly the first frame of every animation loop. In that case, I think because my custom deform-bone setup is “reading” the Two-Bone IK bone locations from the previous frame, there’s a “jitter” at the beginning of every loop iteration where the ankle/knee “snap” into place to follow the UE4 IK system. Is there any way to prevent this from happening? I guess it’s ok if it happens at the beginning of the first loop, but is there any way to prevent it from happening every loop?

[Edit] Or maybe there are better/smarter ways to set up a two-bone IK that includes twist joints?