I had this problem before with GNOME 3.18 (previous thread) but it came back with GNOME 3.20. Where the background is not displayed if Icons are displayed on the desktop.
Last time it was caused by using Numix based GTK+ theme. I am using Adwaita for GTK+, Icons and Cursor.
The only solution I have is after every reboot, start Tweak UI, goto Desktop, and toggle the Icons on Desktop OFF/ON and then it is fine until I reboot again. I can reproduce this on my desktop and laptop.