CollisionShapeFactory adding a base

I load the model in the top of the picture below (in scene composer) and create a collision shape from it

Spatial object = Game.assetManager.loadModel(“Models/objects/”+name+".j3o");
CollisionShape shape = CollisionShapeFactory.createDynamicMeshShape((Node)object);

But I end up with the bottom one. Have I done something wrong thats caused the extra bit? (The capsule is just used to make the object highlighted)

Alternatively, is there a way to make a collision shape from a bounding voulme, like in JME2? I tried CollisionShapeFactory.createBoxShape() but that was a disaster with boxes everywhere

Erm yeah ok. Took the first model in the picture, divided all faces into 4 faces, recreated the collisionshape as per the code and it works fine? So ridiculous