Make sure the disks are correctly redirected in the remote session.
This can be checked in the local resources tab of the client generator.
You can also edit your connection client's settings with this procedure to check the presence of the "-disk on" parameter:
https://www.terminalserviceplus.com/docs/edit-delete-parameters-generated-client
Make sure your antivirus is not preventing the transfer of the print job.
On the server side, you may need to set an exclusion rule in your antivirus for the following path: C:\Program Files (86)\TSPlus and C:\wsession
On the client side, set an exclusion for the following path : C:\Users\Nameoftheuser\RDP6
Check the presence of two universal printer driver.
Open Windows control panel>Devices and Printers. Click on the Universal Printer and click on "Print server properties" and click on the drivers tab.
There should be either the CustPDF driver (old driver from version 9 and below) or the Ghostscript PDF (newest driver) driver.
If both are present, delete CustPDF.
If that doesn't work, you can reinstall the Universal Printer completely in the AdminTool
In the AdminTool, go to Printer and click on Remove the Universal Printer,
Then click on Install Universal Printer (Ghostscript).
If you are using an older version of TSplus, go to add/Remove Programs in the Windows control panel and look for universal printer, click uninstall and reboot.
You can also force the uninstall by clicking on the removeuniversalprinter.exe located in C:\Program Files (x86)\TSplus\UserDesktop\files
You will be able to reinstall the Universal printer after rebooting by clicking on installuniversalprinter.exe