At present, all destination addresses are verified using the USPS address database. This is done to correct minor errors in the address and to make sure that the USPS can find the address that you're trying to ship to. The address that is initially presented when you're purchasing shipping labels is the USPS-verified version of the address the buyer entered.
In some cases, affecting a small percentage of labels, the USPS drops some information from these addresses, typically apartment or suite numbers.
We're actively working on a fix for this issue, and will update this post once we have it corrected.
For the time being, please double-check the addresses on your labels. If there is a difference between the address on your order receipt and your label, you can confirm the information with your buyer and manually edit the label version when necessary.
We apologize for any inconvenience caused by this issue; we hope to have this resolved as soon as possible!