As you are probably aware the USPS has some major delays. If I read correctly the shipping destination was 20 minutes away but that is irrelevant with regards to how USPS routes packages from the originating post office to 1 or more regional distribution centers which may or may not even be in the same state. Due to the shipping backlog the USPS is often times not scanning and things will only show up when and if you have them scanned when you drop them at the post office and then when they arrive at the destination.
I am not sure what postage class you used or the value of the "expensive" jewelry or if you insured it but you can file a missing mail request with USPS 15 days after shipment along with an insurance claim if the package was insured.
Keep in touch with your buyer to avoid a potential INR claim that could ultimately cause eBay to unilaterally refund the buyer, and them eventually receiving the item at some point.
