Sales Invoice - Item Price Changes after submitting and reloading

When creating the Sales Order through Data Import, it comes in exactly as it supposed to do. However one item has a slightly different price by $5. This is ok as it was approved for a one time deal. The Sales Order submits fine with this altered price as the “Ignore Pricing Rule” is checked. Creating Delivery Note/Packing Slip work fine and then creating the Invoice, the item price pulls correctly. However after submitting the Sales Invoice (which posts to the db the correct price), if you either reload or leave the page and come back to view the Sales Invoice again, it pulls from the item price list and not from the sales order which has the slightly different price. How to make sure it pulls from the Sales Order rather than the Item Price list? I needed to cancel the invoice because we forgot to add the shipping costs, but it won’t let me… says “Update” because the price isn’t matching. I tried " Maintain Same Rate Throughout Sales Cycle" which it does, but not on the viewing of the Sales Invoice after it reloads.

Thank you.