Nextcloud - pagesfiles - iOS12 - iPhone

Hi use NextCloud 16 and the current iOS app.

I try to open a pages file with the open with function from the iOS app. This works and I can edit the file with the pages application from apple.

But if I try to store the data, there is no synchronization and after some time there is an error message like: “file could not be stored”. I have set the datastore setting to nextcloud on my phone as well.

Is there anybody who has this working ?

Add:
If I try to create a new document with pages, in this case I can store the new pages doc into the nextcloud. The problem is only if I try to edit an existing document.

Has anybody this working:

Sharing Apple Documents like pages oder numbers with the current IOS App, edit them and store it back to NC 16 ?

Thanks