What's your intention - to append new records in ContactPointAddress or to update the existing records? Also, does the account configured in the Salesforce connector has the write permissions for the ContactPointAddress table?
I understand from your response that you need to add the address to persons already in Salesforce. In other words, some records in Salesforce were missing that address, and you want to fill out the empty field. If that's correct, you need to use the "Update/delete records in Salesforce" action.
The "Export to Salesforce" action creates new records in Salesforce. It doesn't update existing ones.