Printers do not map in session after updating the Citrix Receiver. This causes the ThinPrint Client ICA to malfunction and therefore it does not load in the system tray.
Depending on the installing user privileges and the client architecture, the relevant Citrix ICA Client registry path may have changed.
ThinPrint ICA Client (any version)
Citrix Receiver (any version)
The easiest way to get the ThinPrint Client working again would be to perform a repair-installation of the ThinPrint Client after the Citrix Receiver update.