Recently I had an issue where I would get a blank screen after booting up and starting XFCE from my display manager (LightDM, if it matters). No panel, no icons, no desktop, just my cursor. This began after uninstalling GNOME (and reoccurred after installing i3). As a workaround I could just switch back and forth between TTYs (i.e. Ctrl + Alt + F6 then Ctrl + Alt + F7) and that would finally start up my desktop. But today I have found a real solution.
The solution for me was to delete
~/.config/xfce4/xfconf/xfce-perchannel-xml/displays.xml as suggested on the Arch wiki and on this thread from the Nvidia forums (this also seems to be an issue with multiple monitor setups).
Searching for this issue online yielded very little, and led to me only temporarily solving the problem the first time by deleting all of my XFCE settings as suggested on the Arch forums (do not do that, that is a pain to set back up if you've dumped as much time into your settings as I have). I only happened to come across the solution while reading the aforementioned XFCE page on the Arch wiki. So hopefully I've dropped enough keywords in this post to help the next unlucky desktop-environment-hopper or multi-monitor-power-user that searches for this issue, and if you're that person, thanks for reading.