conflict with role_delegation? RR only works by admin user

I am using to help set up a "membership coordinator" role that can create new users and assign roles to them, etc.
registration_role seems to be working when an admin user creates a new user, but it is not working when the membership_coordinator role creates a new user, although the membership_coordinator has permission to assign roles.

I've glanced at the RR code and don't see any permission checking, so I'm not sure where the issue could be coming from.

thanks for any suggestions or fixes.