[xubuntu] LightDM and Use wallpaper if available not working

OK, so I have 4 systems that are ruing xubuntu 16.04 and all configured about the same, and all use the Variety wallpaper changer.
So, I want the LightDM login screen to use the wallpaper that the user sees when logged in, not a specific graphic or color.

All systems have the LightDM GTK Greeter setting the same. However, on1 of the 4 systems this work correctly. However, on the other three systems the wallpaper shows up for an instant and then the Image selected.

I have looked high and low for what might be causing this problem.

So my question is, how does one configure the lightdm-gtk-greeter.conf file to make this happen.