If your current Magnifying Glass app stops working and is only “Loading” (as e.g. Microsoft’s own), you should try this app.

This is simple Camera Zoom, or Magnifying Glass, application. No filters are present (so less functionality than Microsoft Pocket Magnifier), but you can use it as mirror.
It can be switched between main and front camera (or any other your device are equipped with), you can rotate picture, or make it as mirror.

You can take picture - JPG would be cropped to area visible on screen. All pictures would be saved in Pictures library, subfolder Lupka (in Polish it means: magnifying glass).