Why is my PHaT doing this

When I simulate a joint its fine, but when simulating multiple joints, the joints that are lower on the skeleton tree snap to the root joint.
I have a link that shows the problem.

[Here for small video of the problem][1]

This problem has been occurring since 4.15, I have posted this problem before but received no responses. What I do know is that it has something to do with my character rig from Maya. But, have not the slightest clue as to what is causing it.

[1]: