I am having some issues when trying to use Emacs Ediff as the external diff tool for SourceTree. My external diff setup is as described here: https://www.ogre.com/node/446 . From SourceTree, Emacs is started with the correct files but no Ediff session. Also, if the "Arguments" part of the (custom) external diff command is removed, the exact same happens. So it would seem that the arguments are not evaluated correctly.