[Zubersoft]

No songs should ever be hidden in MobileSheetsPro. If they are filtered out, you can tap the "X" at the far right side of the filters bar on the library screen to ensure they all are displayed. Some songs in your library may not be assigned to albums, which you can verify by going to the Songs tab, tapping the button to show more filters, tapping on Albums, changing mode to "Unassigned' and then tapping OK on both dialogs. 

How did you go about summing all songs in all albums? I'd like to know the exact approach you used for that.

Thanks,
Mike