Some users have reported issues that are caused by corrupted updates from the App Store. We have contacted Apple regarding this issue and they have requested that affected users provide their Apple ID and approximate date/time the issue started so that we can open a bug report with Apple.
We have found that reinstalling OnSong corrects these sorts of issues. Before you reinstall, please be sure that you have a backup of your OnSong library as deleting an app from iOS will also delete its documents and data which contains your OnSong library. You can learn more about backing up and restoring your OnSong library here: http://onsongapp.com/videos/backup
Once you are sure your library is backed up, go to the home screen of the device and locate OnSong. Tap and hold on the icon until an "x" icon appears. Tap on the "x" to delete the app. You'll be prompted that documents and data will also be deleted. Agree to this and OnSong will be removed from your device. Press the home button on your device to exit the editing mode of your home screen.
Tap into the App Store app and download and install OnSong again. Keep in mind that OnSong is free to download as long as you are using the same Apple ID and have not requested a refund. The App Store may also report the app for a purchase price if you are not actively signed into the App Store with your Apple ID. To work around this, you can download a free app to force the sign-in process, or tap on the "buy" button to install OnSong again. If you have any questions about your Apple ID or purchase history, please contact Apple iTunes Support: https://www.apple.com/support/ios/contact/
Once installed, restore your library by importing the backup file and the issue should be resolved.
If you had purchased add-ons, you can restore those purchases as well. To do this, go into the Utilities menu (gear icon) > Account > Add-Ons and tap on the "Restore Past Purchases" button at the bottom. This will have you sign in to your Apple ID if required and then restore the add-ons that you have enabled previously.