Thanks for the lightdm greeter background fix, folks. Not a deal breaker but I’m very glad to get it working again.
BackgroundFile=‘insert wallpaper’s path and filename’
Actually it looks like it’s missing the right config. You seem to need to flip to true the following via dconf:
org.gnome.settings-daemon.plugins.background active true
I actually did the second part first and it did not work, but once I toggled background active to false again, then true again it worked. It should also work for anyone who reads and follows directions in the correct order!