Step one with USPS: have your local carrier pick it up and make sure they immediately scan it in. I have shipped thousands of items via USPS and have never had this issue. And I never drop off at the post office. Why bother when I can get free home pickup.
Now I have a great postal carrier. If not, I'd take stuff to the post office and wait in line to get scanned in with a receipt. I'm not putting a $500 item on the counter and walking out. Not all post offices are busy. In my area, the one that is a mile away is packed. Meanwhile, one that is six miles away is empty. I'd rather drive five minutes and avoid the line.
Note on tracking, ITS NOT tracking. Its delivery confirmation, nothing more. People often call it tracking, but its not. But it will show being scanned in by my postal carrier (which is important to me to maintain top rated seller status on eBay). And sometimes it will show where the package is during transit, but often, that information is not accurate.
+1 Start with the police. File a report. Item was likely stolen off the counter.
Last edited by wrk101; 01-25-18 at 10:57 AM.