There was a huge problem in Oak Creek as I talk to the postmaster in Port Washington about it in December. The same thing happened to me. It is really inexcusable even with Covid and Holiday Rush but my USPS PRIORITY packages I mailed to customers spent 10 days on a truck parked at the Oak Creek facility. I started to send packages via UPS which had a one-day delay.
The postmaster made up excuses about how the packages were put on the truck, used as temporary storage, but then other packages were placed in front of them and the older packages never made it out for about 10 days. Now that is the truth I was told. And if that is it is sad how the post office is run.