Pages and Keynote apps stop opening
We have had Pages and Keynote suddenly stop opening on a few (about 10) of our iPads. These students had been using Pages and Keynote recently.
We use an MDM to deploy our apps and the students do not have an Apple ID. This has only happened on iPads running iOS9.1 and the latest version of Pages and Keynote.
I have tried a forced restart, and restoring all settings.
When I tried an encrypted back up and restore from back up, all the content returned except the files in Pages and Keynote - they were empty but they opened.
Is there something else I could do to recover the data in Pages and Keynote? What does it mean if the content doesn't get restored through iTunes?