The Windows icon setting is controlled by a different setting.
Thanks,
the setting was enabled. I got it to work by turning on the preview pane and refreshing the window, after that I can turn the preview pane off and it still shows the thumbnail graphic.
I'm not sold on Win10
Try the registry hack here if that works: "No Preview Available" - another possible solution - FYI.
The Windows icon setting is controlled by a different setting.