This is exactly what has happened for me, too. "Tracking information is invalid" according to PayPal, case closed in Seller's favor. I had sent my scope back using Australia Post, our national carrier, and I am absolutely sure they do not have "invalid tracking information" so I phoned PayPal on the 1800 number yesterday about this, and the operator had a look at the tracking history of the package on the AusPost website, which clearly shows that the scope went from Australia to China, was unable to be delivered and has now arrived back in Australia. Her answer was that I should appeal the outcome of my dispute, because it was not my fault that the sender was not prepared to accept back the item. She asked me to photograph the mailing labels and markings on the package when it returns to me, then call PayPal again to upload this to form the basis of an appeal. Hope my answer will help you.
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