Won't Insert post_author by Display Name

The new version (3.5) doesn’t seem to accept display names for the post_author field anymore. I could swear that the prior version did.

I experimented with substituting the user login name and that uploaded fine. However, I am automatically generating the csv file with the display names in that field, and would prefer not to have to change each and every one by hand.

https://wordpress.org/plugins/wp-ultimate-csv-importer/