From the GP team comes notice of an issue with Workflow 2.0 Adding additional Document Lines Fields after the Message has already been saved causes incorrect data to show in the Workflow Notification.
Workflow 2.0 Adding additional Document Lines Fields after the Message has already been saved causes incorrect data to show in the Workflow Notification.
Archived post from 2016. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.