FCPX Plugin - No "Generate Music" button

If you see the SmartSound Audio Placeholder in the Generators section of FCPX and can place it on the timeline, but the Inspector window only shows "Published Parameters", then the plugin simply needs to be re-registered with FCPX. To do this, close FCPX, then open the following folder:

Macintosh HD/Library/Application Support/SmartSound/Plugins/

Inside the Plugins folder you should see an app called "FinalCutProXPlugin". Double click this app and it will re-register the plugin with FCPX. Close the window, then relaunch FCPX and try again and it should now work properly.