Files are missing message when using webdav

Hello together,
I just started using duplicati and have a small problem. After creating a new backup configuration I started backing up manually. When I want to backup the same folder again I get the message “Found 3 files that are missing from the remote storage, please run repair”. I checked it and all files are existing. When I try to repair the Backup database I get the following message:
“The backup storage destination is missing data files. You can either enable --rebuild-missing-dblock-files or run the purge command to remove these files. The following files are missing:”
But this file is also existing.

I stored the Backup via WebDav (Nextcloud).
Any Idea what is the problem ehre and how to fix?

Welcome to the forum @Craft

Perhaps you can start by trying this not-yet-answered question from another invisible-Nextcloud issue:

Assuming these 3 files are small discardable test data, you could also delete them, then test the folder.

Duplicati.CommandLine.BackendTester.exe can take the URL obtained from Export As Command-line.

If you prefer to test remote operations manually, you can try Duplicati.CommandLine.BackendTool.exe.