It’s because the animation is still being applied to the Arm. My suggestion is to rename the UpperArm before applying the IKControl, and then rename it back once the IKControl is no longer needed.
I also noticed that in the second clip the head only moved. But in the second clip, the hip and arms Now move. that script is applying an offset of it’s own as well. Changing the name of the arm could break it if it’s not programmed correctly, but if it’s programmed good. This fix will work for it still.
In the old version, the torso and the head moved- the same as the new version. And I tried renaming the arm to something other than LeftLowerArm and LeftHand, and it didn’t fix the problem. Any other ideas?