Thanks , that solved all of my problems. For future reference for anyone reading this thread. Objects with a mass should be created as a dynamic shape. Objects with no mass should be a standard collision mesh shape.
CollisionShape sceneShape;
if (spatial.getControl(PhysicsControl.class).getWeight() > 0){
sceneShape = CollisionShapeFactory.createDynamicMeshShape(spatial);
} else {
sceneShape = CollisionShapeFactory.createMeshShape(spatial);
}