Nextcloud iOS app: Not all files in offline folders being downloaded

Hi,

we’ve been having a strange issue affecting offline files on multiple users’ iPhones and iPads:

When you mark a folder as offline, the app starts fetching the folder contents in the background and the files get the green „offline checkmark“. So far, so good.

However, once it reaches the 2nd or 3rd subfolder level below the offline-marked folder, it just stops downloading at some random point and leaves the remaining files set to „cloud only“.

The files which haven’t been downloaded are (correctly) missing the green checkmark. Unfortunately, there seems to be absolutely nothing you can do to convince the app to fetch all the files that were left out.
To get the missing files stored locally onto your device, you have to tap them one by one, but that is hardly feasible.

Has anyone else seen this issue, or have an idea how to fix it?
Thanks!

Some details/observations:

  • The affected folders and files live in a group folder.
  • A typical offline folder may have 1k - 3k files and 1 - 3 GB total volume (on the server, across all its subfolders).
  • It’s usually whole folders that are being left out.
  • When a folder is left out, all its subfolders are left out, too.
  • The further “down” you browse into the offline folder’s tree, the more likely it is you will find files that were not downloaded.
  • It’s not just a few files here and there that are being left out, but a substantial portion of the folder’s total contents.
  • There are no huge files (mostly office documents, PDFs, JPGs etc).
  • Most folders only have a few dozen files, with a maximum of a few hundred files in a couple of the affected offline (sub)folders.
  • There’s no discernible pattern which files/folders are left out. In some cases, it will descend into the 3rd or 4th level below the offline-marked folder and grab all the files flawlessly, and in other cases it stops downloading on the 2nd level.
  • For a specific folder, the results are can vary for different devices/users.
    On one device, the folder gets downloaded fully with all subfolders and files, but on another device the same folder is missing like 1/3 of all offline files.
  • It’s not caused by a lack of bandwith or local storage - both are plenty.
  • It’s not just being slow to download - you can wait several days and the files are still missing.
    That excludes a cause of server-side overload or congestion.
  • Total data volume in Nextcloud is around 350 GB and 220k files (but not all users have access to all files)

Things tried without success:

  • Remove all offline folders in the app and add them again.

  • Mark subfolders below the original offline folder also as offline (has no effect).

  • Clear the app cache completely and re-download everything.

  • Restart Nextcloud server.

Version info

  • iOS version: 16.5 (current)
  • App version: 4.8.6.4
  • Server version (hosted): Nextcloud Hub 5 (27.0.1) with S3 storage backend and MySQL db

Late, but same for me

Fixed it by completely uninstalling and reinstalling / reconfiguring the app.