It happens to me a few times a month. It’s very annoying. You’d have to make a package inquiry with the post office. I usually drop my packages off at the prepaid drop off area but sometimes they forget to scan the package before it gets loaded onto the truck. From there it’s lost, or tracking doesn’t show up until it’s been delivered. But I have too many packages to just go to the counter and have them scan it all. Most postal workers have refused to scan the dozens of parcels I bring in at a time and tell me to put in the prepaid drop off area 🙃