i'm not sure if you have access to the training manual but i think it suggests that you run with inertial relief if importing from motion
however be critical of the results
in general I would recommend setting up a static analysis based on what you've learnt from motion with your own loads vs importing or applying real restraints vs inertial relief.
i'm not sure if i understand your comment about " The motion simulation works with contact elements and the fixed components from the assembly but I don't know how to pull this across to the stress analysis study."
Is that a separate study?