I'm in the app folder.
I mkdir exports to make an export folder.
I run rake evm:export:service_dialogs -- --directory exports
I get back:

(in /var/www/miq/vmdb)
Error: argument --directory Destination directory must exist.
Try --help for help.

How can this be? I can ls and see my exports folder in this directory.

Now that support for 1.8 has been dropped, there is no need for the 1.8 style Hash syntax. Any place where a Hash is used, it should be using the newer syntax.