I've found that the changes are saved in ~/.config/menus/applications.menu, which is ignored by xfce. Renaming the file to xfce-applications.menu applies the changes -- a workaround.
I've found that the changes are saved in ~/.config/ menus/applicati ons.menu, which is ignored by xfce. Renaming the file to xfce-applicatio ns.menu applies the changes -- a workaround.