When you use a wizard to change to a new design for your publication, some elements in the first design may not be included in the new design. Publisher automatically moves any objects that you modified or that are not appropriate for the new design to the Extra Content tab of the Design Gallery dialog box.
To view objects on the Extra Content tab, click Extra Content.
My current publication's design set is empty.
You must first create a design set for your current publication by adding objects from your publication to the Design Gallery.