AppleTV 2 (black) No folder.jpg Thumbs on SMB Icons

Hello,
i recently added a few more smb sources and put some folder.jpg inside each folder. But the thumbnails don't show up. If I go one folder deeper (for example in my series folder) the folder.jpg works fine.
Before I deleted and added new sources they also worked at this folder level. I also deleted the folder cache.

Any idea?


Edit: I used a folder.jpg from a working subfolder to ensure that the jpg is correct

Solution: I copied all folder.jpg from the sources to the local atv2 and added after <path> in the sources.xml:
<thumbnail>/uri/to/thumb.jpg</thumbnail>