How big is the group you are testing this with?
I tested with a group that includes my test account and another account. They have different email addresses for notificaitons, and when my test account adds the workflow and it is a Task type step *only* the second account is notified (not my test account). For an Approver step, both received the notification. In both cases I just added the workflow to the ticket manually.
So I'm wondering if Task steps for some reason do not notify the account that adds the workflow to the ticket.
Otherwise I can't figure out why it would behave that way.