Just come off the phone from a senior Apple tech support person. They've said it's a bug. I say it's a disgrace, but there you go.
Basically, if you open a Pages file that is stored in OneDrive via the OneDrive integration in the Pages iOS app, unless you manually export it, any changes you make are lost. Forever. With a single press of a button.
It's probably easier to explain if I just show you the steps:
1. Open Pages on iPad.
2. On the left-hand side 'Locations' bar, tap 'OneDrive'.
3. Open a .pages file from OneDrive.
4. Make changes to that Pages file in the Pages editor.
5. Press the 'Documents' button in the top left, because you are done editing your document and/or need to locate another file to work on.
6. Observe the little animation that shows your document 'minimising' into the screen. Say goodbye to the changes you just made to that document. They're not coming back.
7. Frantically look for the modified version of the document via the 'Recents' tab in pages. It's not there.
8. Frantically look for the modified version of the document via the "Pages' folder on iCloud Drive. it's not there.
9. Frantically look for the modified version of the document on OneDrive. Only the old, original, copy is there.
What a mess.
Basically, if you open a Pages file that is stored in OneDrive via the OneDrive integration in the Pages iOS app, unless you manually export it, any changes you make are lost. Forever. With a single press of a button.
It's probably easier to explain if I just show you the steps:
1. Open Pages on iPad.
2. On the left-hand side 'Locations' bar, tap 'OneDrive'.
3. Open a .pages file from OneDrive.
4. Make changes to that Pages file in the Pages editor.
5. Press the 'Documents' button in the top left, because you are done editing your document and/or need to locate another file to work on.
6. Observe the little animation that shows your document 'minimising' into the screen. Say goodbye to the changes you just made to that document. They're not coming back.
7. Frantically look for the modified version of the document via the 'Recents' tab in pages. It's not there.
8. Frantically look for the modified version of the document via the "Pages' folder on iCloud Drive. it's not there.
9. Frantically look for the modified version of the document on OneDrive. Only the old, original, copy is there.
What a mess.