You need to think about the backend operations of other actors in your supply chain.

USPS picking up the basket 2x a day is not enough. They need to scan each parcel individually into their system to mark it as accepted.

If, for example, the postman picks up your basket, tosses it in his truck, and then the truck catches fire, or if your basket falls out the backdoor, or if the truck gets stolen by thieves (more common than you'd think) on the way back to his home post office, your parcel would never actually be scanned into the system.

Just because you've used a process for many years and not had any issues does not mean the process is 100% correct and/or foolproof. Something happened. You can either react and change your methods (for example, asking the postman to use his portable scanner to scan the parcels when they're picked up), or you can take this one on the chin and accept that once every 12 years something like this might happen.

I've been in your shoes, and what I did was reprint and reship all the affected packages. They've never been scanned into the system, and you've already paid for the postage. So why not?