We're syncing the Address table because we're looking for employee ship to addresses. It could be either a corporate building (those are being delivered via the API) or a personal address (and these are the one's not being delivered via the API).

The Invoice Header table delivers a Ship To Address ID for all addresses (corporate or personal) but the join to the Address table breaks because the personal addresses aren't in the Address table.

We are looking for personal addresses to be added to the Address table.