xfce4-screensaver "Floating Xfce" not configurable

xfce4-screensaver 4.20.0 Arch Linux

Without any configuration, Floating Xfce works. Opening the configuration UI for it causes the preview to freeze, with the screensaver becoming blank upon activation. This resolves when clicking "Restore Defaults".

ps ux | grep /usr/lib/xfce4-screensaver/floaters suggests that the process dies when the preview freezes.