Automated Update Request - some fields editable, others not



I am trying to set up an automated Update Request for % Complete updates on a project plan. When I test the automation sending it to myself, the system seems to be randomly selecting what item can be updated. For instance, sometimes it is only the task name, others the task name and percentage complete. As I need it to be the percentage complete and not the task name. The below screen shots are from the same request email.

how can I fix this