Hey, Lord Tim - this just happened to me! Or a variation on it:
I have a set of double-tracked vocals. I decided to use VocalSynch, for kicks. Worked fine until I got to a set in which I had "bounce to clip" for whatever reason, I don't remember. But the clips had no name (that's how I know I bounced to clip at some point in the recent past).
Anyway, for these clips, VocalSynch refuses to "open the editor" or "create the FX Region" or whatever you want to call it. I get the progress bar; the clip flashes, then I'm left back in the Track View with no FX Region, and no editor window.
(By "editor window" I just mean the floating control panel with the "intensity" knob.)
If I try a second time, same thing.
If I use the Inspector to give the clip a name, it makes no difference. Still no editor.
I then saved then entire project to another folder and closed and re-opened SONAR. I successfully opened a V-Vocal "region FX" and made an edit. But VocalSync refuses to open on this clip. I have no idea why.