Problem with Splitting Documents by Bookmarks File names say Part instead of Numbers

Hello, 

I recently got an update to my Adobe Pro and the Splitting Documents feature is labeling my files differently now. Before the update, the files would be like this:

But after the update, the files now have part numbers at the end like this:

I have modified my settings by unchecking the Use Label box and have Use Bookmark names for File Names checked. Does anyone know what I might be doing wrong?