Cubase 8.5 transit vst not working

The VST Transit user name is to be set exactly once when you login to VST Transit for the first time. So when your mySteinberg credentials are accepted and you have registered Cubase 8.5 with your mySteinberg account, the very first time you will be asked for a VST Transit user name. This is not registered with mySteinberg , it is the user name for VST Transit under which you can be found by other users, so you should provide a new, meaningful name here. It does not relate to the mySteinberg account or the mySteinberg email or user name, but solely to the VST Transit membership. As said, you will provide your username only once ever, and it can not be changed thereafter.