Fyi - each time you make a new print or transfer request, a new barcode is generated. But you can print the same barcode multiple times. Older barcodes will not scan at the gate, only the most current barcode will work. So if you uploaded a barcode to stubhub, and then for some reason logged into your account manager, its possible the sold barcode could be rendered void.
This happens all the tome. You create a stubhub listing by downloading the pdf and then uploading to stubhub. While youre waiting for it to sell, you log back into account manager and print a copy for yourself to keep and boom --- the stubhub saved barcode is dead.
So if the barcode that was transferred to the seller was used, it comes down to word against word. So either the buyer is a liar and trying to pull a fast one, or you accidently f***ed yourself. The only other possibility is a 4th party logged into your account manager and stole your tickets.
Any of these scenarios suck, feel for ya