The Mechanical Drawing Rule for Airflow is not displayed with the correct Part definition on elements in the Drawing View only when you modify or change the Part definition on the duct in the 3D model from what it was originally. If this was done, then the drawing view elements will keep the original air flow definition. The DataGroup property will not change even though the correct Air Flow is defined in the rule.
This can be corrected by using the keyin, BMECH REBUILD, after the ducts are modified in the 3D model. Then all of the correct attributes will be displayed in the drawing view.