Perhaps you’ve followed all of the steps here, but when you add an email it still doesn’t appear in your Workspace queue of invitations.
The user you’re trying to add is likely already part of a workspace. Because a Grain user can only have one workspace, they’ll need to have their current Workspace merged with your Workspace.
Contact firstname.lastname@example.org if you need to merge Workspaces, and a Grain admin will do it for you. 😊