You create a project PO and wants to receive a partial quantity. During the post of the product receipt you mark the "Close" checkbox since user would like to clear the reminder. This deletes the inventory transaction corresponding to the reminder, what is fine but leaves the virtual inventory transaction related to Project consumption that was marked against that reminder.

If later user wants to cancel that Product receipt it's not possible due to that orphan virtual transaction "Lot ID is not specified".

User should be able to use the "Close" checkbox in Project POs with no problems and be able to later cancel the Product receipt if required.