Open the JointMover.mb scene inside Maya 2015 and re-save it.
…\Unreal Engine\4.7\Engine\Extras\Maya_AnimationRiggingTools\MayaTools\General\ART\ JointMover.mb
Open the JointMover.mb scene inside Maya 2015 and re-save it.
…\Unreal Engine\4.7\Engine\Extras\Maya_AnimationRiggingTools\MayaTools\General\ART\ JointMover.mb