How to make xfdesktop refresh thumbnails in XFCE?

Before upgrading to Fedora 29 from Fedora 28, I've noticed that my .thumbnails directory was approaching 3GB. I've decided to delete all the thumbnails, thinking applications needing thumbnails would re-generate them on first request. It seems that has worked to some extent (the folder is slowly filling with thumbnails again), but on my desktop (XFCE's xfdesktop) isn't showing them. When refreshing the desktop with F5, that doesn't work, and installing tumbler-extras didn't work either. I'm now wondering how or if I can force xfdesktop to re-generate thumbnails and keep generating them when a new file is being dropped onto the desktop. Or perhaps there is an entirely different solution which I'm not aware of.