Do know that as far as I remember, there is no other report on this issue from others. Perhaps it something specifically in your system. Something might be blocking Deskscape from properly display specific wallpaper.
If you wish, to make sure Deskscape get install properly, you can try, uninstall Deskscape, reboot immediately (important), re-download latest version available in your account product download page: https://store.stardock.com/myaccount/products. Install it, reboot immediately again.
Also, please try adjusting the quality vs performance setting and see if that help.

Thank you,
Basj,
Stardock Community Assistant