When printing, the label was automatically corrected to "Nashville, TN 32172" or some such without my notification or verification. That number doesn't exist, so the package got returned to me and I lose money.
Apparently the correct address is "Madison, TN 37115", I think similar to how Brooklyn is considered part of NYC but technically its own borough.
Had Shipstation notified me of this behind-the-scenes address change, I could have easily googled this and not lost money as well as a week of delayed shipping. Also oddly enough, I've shipped over 16,000 packages in the last 3 years and never encountered this.