When you create and pose a scene, the body positions are based on physics as well as node position, so the pose may shift when you reload it. In the above scene, it looks like they're leaning on a ledge or table or something. So it's likely that when you posed them, the elbows were where they were because the table was preventing them from moving to where the nodes wanted them to be. If you had turned off collision for the table, the elbows would have been free to move to the natural position you see here.
When you load the scene, only the saved node positions are used to position the model. Not the actual body position, constrained by collision with other scene objects.