How to keep contract invoice date in closed period as invoice date

Summary:

We create a contract invoice with the invoice date in open AR/Projects period. We keep the invoice in draft status. Then we close the AR and Projects period. We regenerate the draft invoice still using the same invoice date, which is in the closed period. When we approve the contract invoice the invoice date suddenly changes to the system date. What drives this change in the invoice date? We actually need the original invoice dtae (in the closed period) as the actual invoice date (in Receivables). Is it possible the invoice date remains the original invoice date rather than unexpectedly