This article shows you how to complete manufacturing and invoice from the case record.
1) Open the case record
2) From the Case Record click "Complete Manufacturing"
3) Scroll down and click "Edit Invoice" or "Approve & Invoice"
*Please note, if you delete the invoice, it will not show up in Create Invoices queue until the manufacturing is complete. You will need to recreate from the case record if you want to invoice before the case is completed.