Child is not following parent animation


I’m testing soft body animation with simple cylinders. I cut the top of a cylinder (a circle) so that it deals with all the physics stuffs, and let the rest of the cylinder linked to the top part using ‘child of’ constraint. When I move the top part, the bottom part follows it well. However, it doesn’t follow the parent when I apply soft body physics to the parent and it consequently falls down to the plane.

Am I missing something or the constraint is not working with soft body animation?

p.s: those two parts are intentionally separated. Thus, a comment like merge those two and apply physics is sadly not helpful.

simple.blend (863 KB)