Answer
Look for ROWSTATE on the SHIPMENT_TAB table — that's the actual underlying field tracking a Shipment's status, rather than a differently and more obviously named 'Status'-style attribute. As a general troubleshooting habit, when a Logical Unit's status field isn't showing up under an obviously named attribute in the event-builder's field list, checking that LU's actual base table for a ROWSTATE column is a good first thing to try.