Hi @Paul_Baxter
We’ve had reports of this happening during an iOS update (more info here: Data Missing After iOS or iPhone/iPad Upgrade/Restore). I’ve also heard of it occurring during an automatic update, if the application doesn’t complete the update. Do you happen to have automatic updates enabled and, if so, do you have the “Use Cellular Data” enabled under Settings -> iTunes & App Stores?
Unfortunately there isn’t much that we can do on our end to prevent this from occurring. It may be helpful to turn off automatic updates. We recommend regularly backing up your data (glad to hear you’re following this practice) and periodically taking an iTunes backup.
I know it’s been a while since you posted this, has Codebook been inadvertantly deleted since then? If so, could you try turning off automatic updates (if you have them enabled) and see if it prevents it from occurring again?
Cheers,
Micah