Note: This issue is resolved in Soundtrack Pro 1.0.1 and later. Update to the latest version of Soundtrack Pro for best performance. Use Software Update or download updates here.
If there isn't already a "Scripts" folder at ~/Library (where "~" is your home folder), Soundtrack Pro does not create one during installation. Because of this, when you create an AppleScript in Soundtrack Pro and try to save it, the save path won't point to ~/Library/Scripts because a "Scripts" folder does not exist there. If you save it anyway, you won't be able to access the script through the AppleScript menu.
To resolve this issue, in Soundtrack Pro, choose Open Scripts Folder from the AppleScript menu. This will create a Scripts folder in your home folder's Library folder (~/Library/Scripts) and a Soundtrack Pro subfolder within it. Now any AppleScripts you create in Soundtrack Pro will have the path, ~/Library/Scripts/Soundtrack Pro.