This is still a problem for me and I am just 12 days from launching my site (April 1st target date).

I also have this issue open in the Drupal.org Uberacrt queue but it isn't getting any attention either: http://drupal.org/node/234781

I've tried creating my own Workflow-NG rules to force a role assignment for my membership product type but it's still not happening. I also tried using "Pending" as the trigger for the role assignment rather than "Complete" but still no luck.

Can anyone help?