This is an interesting request. Invoices, as they are set up now in the Purchasing page, should be entered or checked-in once the products are received into the venue.
It’s a good idea to add a “paid” option if payment for received purchases is handled at a later time. We will bring this up to our Product team.
Great idea! As we continue to make improvements to the Purchasing page, we will highly consider the ability to sort invoices.