SAP ByDesign - Navigate to Sales Order (OBN) shows empty screen

We have a custom BO with an ID field containing a Sales Order ID:

[Label("Sales Order ID")] element SO_ID:BusinessTransactionDocumentID;

On the OWL I select the SO_ID column. It's Text property is ./SO_ID->http://refsystems.sap.com/YM2VUC1FY_->Root-~SO_ID-~content

In the DataModel "/Root/DataList/SO_ID" is bound to "http://refsystems.sap.com/YM2VUC1FY_->Root-~SO_ID-~content"

I set it's DisplayType to "Link".

On Navigation I set the OBN tab to the following:

• Namespace to http://sap.com/xi/AP/CRM/Global
• BOModel: SalesOrder
• I select SalesOrder in the object-tree
• Operation: Open
• It auto-selects /SAP_BYD_UI/SystemPortTypes.PTP.uicomponent as PTP
• and OpenByKey as Reference
• I Bind to /Root/DataList/SO_ID
• NavigationStyle newWindow

Then I confirm the OBN dialog with Ok and Save and Activate. I then open the work center of the object in the browser. I see multiple lines with a filled in Sales Order ID. I verify that the Sales Order in question exists. I click the link. A screen called "Sales Order Overview" opens, but all the fields are empty.

Why?

How can I fix this?