Maintenance update.
The app uses the standard iOS file browser, and we recommend saving any current documents and closing the app prior to updating. On first launch, if it opens in the "Recents" files tab, then browse to "On my iPad" and then to this app's documents. If the app were not fully closed prior to updating then the documents folder may appear empty when first opened, in which case close the app in the iOS home page and relaunch it.