Batch create did not process the whole file, and with those it processed, did not assign a user role

I used batch create to try and upload about 5,500 users to a site with buddypress and multi-blog capabilities. I don't want the users that are uploaded to have a blog (until they individually create one) and I wanted to assign each as a subscriber to the main site. The CSV seemed pretty simple:

null, null, username, null, email_address, subscriber

When batch create processed the file (over 3 hours of time), it had added 259 users...none were added as main users to the main site - I could only see them in the super admin user area, not the user area of the main blog.

How do I get all 5500 records entered as subscribers of the main blog/site?