I found another way to include paragraph numbers in documents already loaded into Nvivo 12.
right click on the file
select export from the menu. The export dialog box has an option for including paragraph numbers and exporting to a Word format
export the file to a folder on your computer in Word format with paragraph numbers.
import that file back into Nvivo
If this is possible (it is i tried it), is there a way to add the paragraph numbers without having to export?