themes – Why is Gnome theming broken after switching to a XFCE session?

I have both installed and I typically use GNOME, but I wanted to try something in XFCE recently, so I switched for a day and then switched back.

In the past, this has been no issue, but now, inexplicably, GNOME theming is broken. Changing the theme in the system settings from light to dark, makes no difference for most applications (including those using libadwaita.

In fact, gsd-settings crashes when I do this, along with several other applications. I can no longer get them to respect my theme settings (accent colour, dark/light mode), and I can’t seem to find a solution in clearing GTK settings in .config.

Any idea what causes this, and what to do about it?