USCIS Chicago Lockbox

[indy49]

I mailed my mom's AOS packet on 3/1/2021 via USPS to the following address.

USCIS
P.O. Box 805887
Chicago, IL 60680-4120

It reached there on 3/4. USPS tracking showed it as "Arrived at Post Office" and "Ready for pickup".

But for some reason today, it shows as...

Status
Delivery Attempt: Action Needed
Reminder to Schedule Redelivery of your item before March 17, 2021​

​

Does anyone know what went wrong? Has anyone else experienced this before?