WTF with USPS

When I tried to file, the web site states that it's past the 15 - 60 day time period, and I sent the package on 12-17-18... WTF????
That's an easy one. You haven't waited the 15 days yet. If you shipped on the 17th, today is the 28th that's only 11 days. Give it a few days then attempt the online claim. But you should be able to file in person. At least you could before I retired.