OK, I know you need to run Melodyne all the way through a song before importing audio to make sure it recognizes tempo changes.
 
The issue I am having is that Melodyne sounds fine when playing the track, but when I export it, the voice is slightly out of syunc to the track.
 
Note that I am using Sonar X1 and a purchased copy of Melodyne Assistant.
 
Thanks for any help.
 
EDIT: Seems OK *if* I don't use fast bounce.

I think the most common way of using Melodyne is to render the track before exporting it.  Have you tried that?

I agree with Lynn, I render every edit I make using bounce to clips.
It seems to help with stability as well. The way I look at is, if your fixing a clip using Melodyne then the orginal wasn't worth keeping anyway  so why not render it.

You can (should?) also create a copy of the original track (archive it) before you start editing, that way there you can go back if you need to.