I am using wordpress 4.9.5, CiviCRM 5.0.2 and CiviCRM WordPress Member Sync 0.3.5. When a new user signs up, and selects register on behalf of an organization. The user role does not sync, stays at the base level. If the user does not select this option, the sync works as configured.
I have double checked mappings, and they are all correct.