[Zubersoft]

Do those songs use a blank page? There is no file to export in that case, as it's all just stuff that is rendered in the application itself. You would have to export the song to a PDF to get an actual file. To do that, long press the song on the library screen while running MobileSheetsPro on the device and tap Share->Export files. That will generate a PDF for you. The companion app doesn't currently have that functionality. The Windows 10 version of MobileSheets can do that though.

Mike