This is a very strange one.
When I open Trash, it opens Gimp saying,
Gimp Message Opening 'trash:' failed. Can not recursively copy directory.
I looked in Preferred Applications and found that the File Manager was set to Gimp.
When I changed it to Thunar, my Trash started working properly.
I wonder why Gimp is even offered as a pick?
It is certainly no file manager.