Now, while I don't consider myself a genius, I feel reasonably intelligent enough to be able to accurately follow a setup installation guide.
However, when installation guide requires that you perform an action on page 75 to successfully get something on page 42 to work, something is seriously wrong.
Specifically, in Epicor's TechRefGuide_MultSite_905602.pdf, it asks you to "Test the Communication" by creating a new customer, marking them Global, save, and then:
"The Multi-Company Process transmits Customer and ShipTo records from that company and sends it to the other companies."
No, it doesn't. Skip to page 75, section "Link Global Records".
What the previous section should have said was:
1. Create the customer, mark as global, save.
2. Goto External Company Maintenance, and choose the child company, and choose Action -> Initialize Multi-Company...
3. Switch to child company, open Customer Maintenance, and choose Action, Link Customer...
4. Search for the customer you created in step once, and click Link.
Hopefully I have saved you the 2 days I wasted troubleshooting this issue.