PDF-Thumbnails not working

[f00b4r]

Hi. I am primarily using Foxit for my PDFs.
Unfortunately, the thumbnails are not showing.
I followed the FAQ: https://www.xyplorer.com/faq-topic.php?id=PDFthumbs

• I checked the cofiguration
• I installed Sumatra
• There is no Adobe Acrobat Reader

Any ideas? Preview-pane works great. Its just the thumbnails

[highend]

Probably a problem with Sumatra...

Installed Sumatra PDF 3.5.2 (with shell extensions), refreshed thumbnail cache: No thumbnails
Installed PDF-XChange Editor 10.4.3, Build 391 (free version, ofc also with shell extensions), refreshed thumbnail cache: Thumbnails^^