TL
R - have you had a chance to talk with your carrier her/himself? That's what I did last time I had something like this happen. I'd also filed a case with the USPS online, but didn't get a response for several days. The day after the item was "delivered", I managed to catch my postie, and asked him about it. Next day, there's the item on my porch. Turns out there was a substitute carrier the original day, who delivered it to the same house number, two streets over.