iOS App on IPad don‘t Download or Open Files

I have a new and my first IPad, here I have downloaded the Nextcloud App and also Word and Excel on my Nextcloud server is Collaborate running and with windows or Android it works all fine.
Version of iOS: 16.6
Version of Nextcloud (snap): 26.0.4

Now to my problems with the iOS-App:
I can login and see all files in the app and also via the Files App.
When I want to download/open a word document, word opened but shows a white paper.
Also when I go back to Files, he shows me that the file is not downloaded.
When I go know into the Nextcloud App and klick on the same file he download it and after that he transfer me to my server and says, that the file doesn’t exist. ← That’s the collaborate, when I disable it in Nextcloud he show me a perversion and I can open it with word. But here word says, that the file is protected and I have to save it lokale.

When I now go into Files-App it shows me, that the file is downloaded and I can open it with word and can edit it. But he doesn’t safe anything. So when I leave word and look on Nextcloud he doesn’t show me the new version. Also when I go back to word, word says to me that he can’t find the file anymore. (I think it was saved in the cache and not on Nextcloud, and after closing word he deleted it).

Also I have seen, that when I open a file in the Nextcloud App it will be “deleted” in the Files-App. So the App shows that file less, but on the server it’s still there.

What I have done:
Reinstall all Apps
Update and Upgrade the server and look after a new version for Nextcloud snap.
Disabled the Files-App including
Disabled the “Collabora Online - Built-in CODE Server” and the “Nextcloud Office”.

Do anyone have an Idea what that reason for that problem?
On Android and Windows it works all fine.


Edit: Excel seems to work. But I have still the problems with word