Symptoms

Workflow is setup with SmartObject event (PDF Converter > Create PDF from URL), the first time I run the workflow for the day, the generated PDF is blank.
 

Diagnoses

This issue is when a form is rendered on a browser in which IIS is reset, but the form is not reloaded. If the form is backed by a workflow in which contains a PDF conversion SmartObject event that is triggered by a button click on the form, then the PDF will be blank.
 

Resolution

This is a known issue. As a workaround, enabling UseSerialization= true on the PDF converter service instance via the SmartObject tester tool resolved the issue.