You are probably using an old 32-bit version of UVI Workstation in Cubase 64-bit – this is a VST bridge issue.
Please locate this plugin file named 'UVIWorkstationVST.dll' and remove it from your VST folder.
Download and install the latest UVI Workstation which is now 64-bit only (more information here) then select your VST folder during the installation process. You may need to rescan this VST folder via the Plugin Manager in Cubase.