Check version of iPrint client on the workstation ( right click iPrint icon in system tray and go to settings to see version level ), it should be version 5.32
If version of iPrint client is prior to version 5.32 then upgrade it
Current iPrint client can be downloaded from http://<AdminServer>/ipp
Uninstall iPrint client on the workstation using Add/Remove programs in Control Panel, reboot the workstation then reinstall iPrint client version 5.32
CAUTION : uninstalling the iPrint client will delete all iPrint printers from the workstation, so make note of iPrint printers currently installed on the workstation BEFORE uninstalling the iPrint client.