Did you get a reason from USPS on why it was sent back after reaching your local post office?
There is a reason, but you’re unlikely to hear the actual reason.
I have had this happen recently with an Estervals order as well as a domestic order. In both instances the orders were within 1 mile of my house but nevertheless scheduled to be sent back to the senders. Only a close watch on the shipping progress and a quick trip to my local P.O. prevented the packages being returned.
In both cases I was told there was insufficient address to deliver and in both instances once I intercepted the packages and checked the shipping labels the addresses were perfect. Also, in both cases, I pointed out the address was good to the counter person at the local PO and asked what they thought the problem was and... they didn’t know.
One did share that someone, she couldn’t know who or why, had written:
NONDEL on the package indicating it was non- deliverable and once someone at the P.O. does this, for whatever reason, all attempts to complete a delivery cease and it ships back to sender ASAP.
My advice is to enable both e-mail and text updates on international USPS shipments and then be prepared to intercede quickly once they hit town, in the case of my Estervals order it was two hours from the long trip back to Deutschland.