- Go through ALL IE settings ("Security", "Connections" and "Advanced" tabs in the "Internet Options") and ensure nothing is blocking the PDF generation,
- Ensure all servers' hostnames appear in the list of trust sites in IE.
-Check for the IE version and PDF Reader versions which compatible with 9.3.1 version.
Can you check the user provisions/access to HFM application, if possiable try de-provision user permission and re-provision check if this helps to fix the issue.
You can try a quick test :
Log into FR Studio with issue existing user and try to create new FR Report using same HFM application check in PDF data user able to view any data.