No HEIC thumbnails on Windows w/ VirtualFiles

Hello all,

I use NC 24.0.7 (own Ubuntu server), Windows Desktop Client 3.6.2, Windows 10
(all up to date)

On Windows 10, in Windows Explorer no heic thumbnails are shown to me, only the program icon is shown.
This error only occurs when the heic file is inside a NC synchronized VirtualFiles folder! As soon as I move this file to another location (which is not VirtualFiles synchronized) the thumbnails is shown immediately. As soon as I move this file again to a free folder which is synchronized with the NC client VirtualFiles, no preview image is displayed.

  • The thumbnails is never reloaded (not even after hours or after manually refreshing the view). In non-synchronized folders the image is always (!) displayed immediately (after 1s).
  • all VirtualFiles have always been downloaded and/or enabled in the folder “Alway keep on this device”.

My Windows is not modified (notably), the HEIC and HEVC extensions are installed (and working, otherwise it would be displayed in non-sync folders).

What I already tried

  • Clear the Win-thumbnails cache. No success.
  • un/reinstall the HEIC & HEVC extensions. No success.
  • delete the thumbnails db-cache files manually. No success.
  • Check reg. entries if heic is displayed. Everything correct.

Is the problem known? (I could not find anything).

Any (more) ideas for a solution?

Thank you very much

You need to understand that virtual files means the files are not actually on your system until you open them. It can’t show a thumbnail of data that isn’t there. It would have to download and read every file first.

Try right clicking on the parent folder and under Nextcloud make that folder available offline. This means it will always download files in that folder and keep them available. Maybe then it can how thumbnails. Not sure if it will but it’s worth a try.

Thanks Karl, I had forgotten to mention that explicitly. Of course, all VirtualFiles have always been downloaded and/or enabled in the folder “Alway keep on this device”.

I’ve been using this feature for ages (in OneDrive) and also for a long time in NC. I have never had any problems with it.

In OneDrive, the thumbnail of HEIC files in VirtualFiles folders works fine. Although the file is only available online (Free up space), once the preview image is created.