DTTG 3.2.4 doesn't download database files although the database is set do "download all" - folders and previews are being synced

Hi. I’m facing a weird issue with DTTG 3.2.4: files aren’t being downloaded although the database is set do “download all” - folders and previews are being synced. When I try to open an individual file I can see the preview and the “download” button below but pushing that button just shows the “download in progress animation” for about a second or two. After that it disappears but the file is still not available.
I’m using a WebDAV-Server for the sync. The strange thing is that some databases which are in the same Sync file (dtCloud-file) are being synced properly while others are not. Deleting the corrupted files on my iOS devices and making them available again thereafter doesn’t help.
I’m running out of ideas. What can I do to get my files back? Help is very much appreciated.

Is an issue logged in DEVONthink To Go? In addition, are these indexed items?

No issues are logged, items are indexed.

Is synchronizing of indexed contents enabled on the Mac? See settings of sync location.

Welcome @messmer

You mentioned corrupted files in DEVONthink To Go. Can you clarify this?

Also, have you done a File > Verify & Repair on the database in DEVONthink?

Yes, synchronization of indexed contents is enabled on the Mac.

Guess you got me wrong. Files aren’t corrupted, they are just not transferred to DTTG although I’ve selected “download files: always”. DTTG syncs the folder structure and the previews as if I had selected the manual download of files. But even then, tapping on “download” the specific file doesn’t do the trick. As mentioned in my initial post, I just see the “download animation” for a second or two and that’s it. - No issue reported in the protocol, just nothing.

Yes, I did “Verify & Repair” the database in DEVONthink on my Mac. - Performed successfully without any issue.

Just to verify…

Is there a triangle on the sync icon in DEVONthink To Go’s bottom toolbar? If so, touch it and tell me what it reports.

No, just the cloud symbol, no triangle.