I’ve just realised… You don’t get an SMS for dropping off do you? I’ve never ever had one in hundreds of boxes. I do get a “booking” confirmation.
Even if everything went wrong (innocently) the UPS driver would have still picked it up which would have also triggered the tracking to stay or add another incident. If the UPS driver never picked it up then it would still be at the shop.
Hence my comment of “innocently” - something is wrong with your situation and it only makes sense if you have made a slight error / not received the SMS you think you have AND someone has bagged it. As regardless of what’s gone wrong as long s it has a label then it would turn up t Amazon or at least be on the tracking.