Hi Jackson,

Please preview the Sales By Product (Summary or Detailed) report and click Edit to access Report Designer.

In here, select Report > Joins > Click the link between INVOICE_ITEM and STOCK and change both Join Types from Inner to Parent Outer > OK.

Then click File > Save As and save your report into My Invoice Reports.

You can then run the report via Invoices > Reports > My Invoice Reports and it will show S1, S2, S3 and M lines.

I hope this helps.