Dockx not launching on login

Starting yesterday, dockx (dockbaarx) has stopped launching on session login for XFCE. It is listed in the Session and startup menu and is set to launch on login. This had been working until yesterday but now will only launch when I open it from the menu.

You mean this AUR package http://aur.archlinux.org/packages/xfce4-dockbarx-plugin ?
Rebuild it.