I'm sorry to hear of the OP"s loss, but let's be real.
The USPS delivers many millions of packages annually, with very little loss of any kind, so this single example isn't cause for a broad based indictment.
As noted by others, the OP didn't make sure the package was scanned as received, so now has no way to file a claim. In all fairness the USPS has the burden of proof of delivery, but ONLY after there's proof that they accepted the package. This is the same rule that applies to all common carriers, and is common sense.
So, the OP should notify the postal inspector because that's his only option. Since there's no scan record at all, the possibilities are limited. Taking the OP's word at face value, the package had to have been stolen at the post office, by the driver delivering it to the regional center, or by someone at the intake area of the center. Had it moved beyond that it would have been scanned.
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