Did you restore the backup of your iPhone from iCloud? If so, can you please verify that you have looked in the "local" section of the Document Picker for these files?
Yes, I did look in the Local list, but it's empty.
Ok - unfortunately, the restore from backup is not something we (the app) have any control over. If that did not work, you will need to try Apple (I recommend an appointment at the Apple Store Genius bar). Another possibility is that these files were stored in the DocumentCloud instead of local. If that was the case, you would need to log in to your Document Cloud account again.