On Windows, Cubase may blacklist UVI Workstation or Falcon by mistake, and may also crash when trying to re-activate them in the plug-ins manager.
In this case, here is the procedure to reset the blacklisted VST plug-ins:
Make sure that every Windows Updates have been installed to your system.
Navigate to this location, where [xx] is the version number of Cubase:
- Delete the file Vst2xPlugin Blacklist Cubase.xml.
Open Cubase in Admin Mode – right-click the application then select 'Run as administrator'.
If required, re-scan your VST locations in Cubase's plug-ins manager.