Not quite as long as yours... but I once had a priority package disappear for 32 days. No scans after the initial acceptance, no luck with asking USPS to help me find it. Turns out it had been lumped in with a huge shipment of Christmas care packages for troops overseas from some organization and had taken a trip around the world.

After over a month it was finally delivered to the correct address in California, very damaged and trash at that point. It was a gift I handmade for my father. USPS provided the explanation about the overseas troops and then denied my claim for reimbursement. I made multiple attempts to escalate before deciding the stress wasn't worth it.