When you export prospect ratings in a constituent export, you can only filter based on the the source of the rating. BB, by default, has named many ratings with the same source - Blackbaud Analytics - NXT, but has named then different categories. You cannot filter criteria based on the category. Therefore, if not all your constituents have all of the same categories, your export to a spreadsheet does not work correctly. The columns do not align on all the rows properly.