Collapsing trajectories in 3dsMax. Movement wrong on xy.

"Collapsing trajectories in 3dsMax. Object incorrectly moves on the xy plane."

I have created a bone based IK animation for my character in 3ds max. I want to export to Unity. In one part of the animation I move the pivot of a bone from the base of the spine to the foot of my character using Motion->Parameters->Subobject->Pivot Controls.

When I was finished animating I selected all the bones and Trajectories->Collapse.

Most of the animation collapses correctly into the correct keyframes. But in the part of my animation where I move my pivot, my character moves out of place in the xy plane after collapsing.

Is moving the bone pivot location compatible with collapsing trajectories? Is there some other way I can move the pivot so collapsing trajectories doesn't strangely move the character on the xy plane?