After upgrading to Ubuntu 20.04 featuring Gnome 3.36, the lock screen displays a solid purple color, instead of the blur-over-wallpaper effect. How can I fix this?

Gnome 3.36 removes the separate configuration for lock screen wallpaper / background, and replaces it with a feature that uses the existing desktop background and applies a blur effect on top, as discussed and as seen here. However, this is not the case on my instance.

My instance shows a solid purple background on the lock screen, while the system settings app correctly removes the option for two wallpapers and only allows the user to select one. Opening up Gnome Tweaks, however, shows two wallpaper settings (desktop, lockscreen), but the lockscreen setting is ignored.

Attempted Steps

• After the upgrade to 20.04 I re-enabled a repo that I thought was for the PopOS icon package and updated accordingly. However, looking through my installed packages I saw there were a number that were forked from Ubuntu and versioned like *ubuntu1pop0. This may (or may not) be the cause of the problem, I'm unsure. I downgraded all the packages I could find back to Ubuntu versions, and disabled the repo.


• I purged and reinstalled gnome-shell and gdm3


• I tried using update-alternatives --auto gdm3 and other update-alternatives commands, but no luck and I don't exactly know what I'm doing with that.