I’ve never used soundtrack pro for round tripping so take my advice with a grain of salt, but I know that if you use motion project files or livetype project files, the media manager will NOT copy/move all the necessary files.
Thank about it this way — the media manager is only going to move your soundtrack pro “project file” – but not any files that the project file is linking to. (side note: YES, serious flaw – thumbs DOWN FCP team!)
Solution: Can’t use media manager unless you render out AIFFs of your soundtrack pro work. OR – just manually copy over all the files that sountrack pro needs after the media manage is done.
daniel