The gauges don't persist across scenes. When you create a gauge and move to another scene and back to the map, you have to recreate that gauge again. See implementation in common event #1 where it continuously checks if the hp & mp gauges are present in the map scene, if not, then it creates them. These are done automatically with event-tied gauges because it checks for the necessary comment to reconstruct the gauges once the event loads.
I have pushed an update for the position fix (v.1.0.1).