eBay does not retrieve tracking info from USPS when the tracking number was issued by a new PC Postage vendor. You can see in these screenshots: The tracking number is valid, and USPS shows that the package was delivered. ![Tracking is good](
http://i.imgur.com/vhgRwd9.jpg) However, eBay does not show any tracking info for it at all. ![eBay no tracking?](
http://imgur.com/UeTxh05.jpg) Historically there have only been a handful of registered PC Postage vendors. I'm guessing that there is a regex in eBay's code somewhere that checks USPS tracking numbers for known source identifiers (belonging to Endicia,
Stamps.com, Pitney Bowes etc) before attempting to fetch tracking info from USPS. However, there have been several new PC Postage vendors added in the last year. Please escalate this issue - many sellers' TRS metrics are being negatively impacted by this issue and many more buyers are not able to see their order tracking status from the eBay interface.