Hi @Richard Lynn Abbott
If you saw only 18 names eligible for indexing on your batch image, then you don't need those extra 12 blank entries and should delete them by clicking the trashcan icon in the middle of the horizontal toolbar and selecting the option Delete "all blank entries."
Each project provides a default number of empty entries - 30 in your case. You don't need to use them all. If you need more than 30 for another batch, you would use the + sign icon to the left of the trashcan to add as many as you need.