Assigning licenses via Username on import

[J-Ingler]

Just the other day I was uploading large CSV files, and assigning licenses to users based upon their username. Now when I try to do it, the Username (and email, for that matter) options are gone, and seems to be replaced with a "Checkout to: Full Name" option.
Anyone know of a way I can assign licenses based on username? Has this feature been removed? (I checked the release notes, and didn't see anything about it). Am I missing something?
Any and all help would be greatly appreciated!