As stated in the subject line I selected a different background picture but nothing updates even after closing system settings?
Check what is really written to
org.gnome.desktop.background. I see the effect of changing wallpaper immediately. But if I change the background to solid colour, it gets always black:
I found, that it writes the colour in
rgb(...) format to gnome settings:
If I fix the value format in dconf-editor to
#..., I see the right background colour. Setting
#d0d0d0 helped in my case.
If you cannot select a picture, you can have a look if the actually written path is correct.