The tracking detail may name mailbox, parcel locker, front desk, agent or another delivery point. Copy the exact qualifier and time, verify the shipping address, then inspect the corresponding place. In a multi-unit building, ask who controls locker keys and whether reception logs parcels. Do not accuse a neighbour or carrier from a scan alone.
If the item remains missing after the USPS waiting point for that status, use the service-request route described by USPS Where is My Package? and keep its reference. Give the local Post Office the tracking number, delivery qualifier, address, time and physical description of the parcel. Ask whether the carrier can review the delivery point; do not request or publish private location data about another customer.