When you save the project file with the host application (DAW application), the production content (vocal part) of the Piapro Studio plug-in is also saved.

If you want to save only the vocal part, use the Piapro Studio plug-in [File]> [Export] to export a Piapro Studio song file (.ppsf) or VOCALOID sequence file (.vsqx).

* Please check here if the edited contents of Piapro Studio are not saved in Studio One.