My mistake. I was translating the hip instead of the body, on the Z axis. I'd switched to hip to show that only the Y had translations in the pose. Translating the body, the pose works correctly.

So you have to translate the body, not the hip, and the pose should work as intended. If you translate the hip, even without body trans saved in the pose, the figure will pop back to zero position.

Now what is it that causes morphs to revert to zero?

 

~Shane