Mojave keeps reverting wallpaper

So I have two virtual desktops on my MBP running Mojave. I open System Preferences and set one desktop to a directory of images that is supposed to rotate randomly every hour. I close System Preferences, go to the second desktop, open System Preferences, do the same thing except with a different directory of images. Now, when I close System preferences and go back to virtual desktop 1 the wallpaper reverts to a default Apple one (ugly shapes). Switch to virtual desktop 2 and it does the same thing!

What the crap?!?!?

I've deleted the following file multiple times (logging and out and restarting afterwords):

~/Library/Application Support/Dock/desktoppicture.db

However, that doesn't seem to help at all. Since "repairing permissions" in OS X isn't a thing anymore I don't know what to do other than continue to look at the fugly "shapes" that Apple calls wallpapers!