When adding a region code manually, ensure that the region code is different than their address.
For example, if a person lives in Ozaukee County, the region code scheduled job will place their home address in the Milwaukee region. To make this person part of the Waukesha chapter for chapter mailing purposes, you must manually add a region code as Waukesha (rather than Milwaukee).
But if you manually add Milwaukee as the region code, it will blow up the scheduled job due to a duplicate data violation. Consequently, none of the addresses in CRM will have the region code populated.