When assigning a Provisioning Role to a user in the Identity Manager UI, the task shows that the AssignProvisioningRoleEvent is successfully completed in View Submitted Tasks. However, the role is not actually assigned to the user. Assigning the same role via Provisioning Manager successfully adds the role to the user.
In the IM Management Console, check the Provisioning Directory for any mappings to non-existent attributes in the Corporate user store, which can cause this behavior. If such mappings exist, remove them, or add the relevant attributes to the Corporate User Store.