Editor controls not appearing

I’ve just got Cubase 9 and have hit a problem with one of my projects. The controls (Vari Audio etc) don’t appear when I open the audio editor either in the lower zone or full screen. This isn’t happening on any of my other projects-- at least, ones I have tried. The control panel appears but it is empty. Is this a bug or have I missed something? I have of course checked the editor tab in the left zone. The project in question was recorded originally in an early version, possibly Cubase 7, but it was modified in 8.5 without problem.