Can existing data from enumeration stored in process spec be migrated to new enumeration field stored in database?

Is it possible to migrate attribute data from an enumeration field stored in the repository to a new enumeration field stored in the database?  The xml template for importing from csv doesn't seem to be the same as the old way from 3.0 of migrating the data to a new enumeration field.

Existing Enumeration field stored in the process spec is called Customer and the new one stored in the Database is called customerName.  I've tried both the literal value and label for the source and existing values on database side and non-existing values.

Each time I get no errors when importing but the data doesn't get transferred to the new field.  Is there any documentation on doing this or is it even possible?

-->
    <attribute sourceId="Type" targetId="Type">
        <value sourceId="APAR" targetId="APAR"/>
    </attribute>
    <attribute sourceId="Id" targetId="com.ibm.team.workitem.attribute.id">
        <value sourceId="99643" targetId="99643"/>
        <value sourceId="99644" targetId="99644"/>
        <value sourceId="99660" targetId="99660"/>
    </attribute>
    <attribute sourceId="Customer" targetId="customerName">
        <value sourceId="Customer.literal.l2" targetId="Aetna"/>
        <value sourceId="Customer.literal.l25" targetId="IBM Internal"/>
        <value sourceId="Customer.literal.l46" targetId="Other"/>
    </attribute>
</mapping>