Once an item has been received, and the basket is open for whatever reason, the received item order line can be cancelled. You should not be able to cancel an ordered item that has been received, you should have to unreceive the item before you can cancel it. To recreate: 1. Set up a basket with multiple items in it 2. Close the basket and receive an order 3. Re-open the basket and click cancel order on the received item 4. See that the received item has now been cancelled.
I think it was fixed in version 20.11.00 see bug 6819 *** This bug has been marked as a duplicate of bug 6819 ***