Has this happened to you?

I shipped out a group of packages on 31 of January, I checked them on the app later, and all of them had been “accepted at USPS” facility that same night except for one. It’s now been 4 days and all my other packages have been delivered. Except for that one and it still says it needs to be shipped. What do I do?

I shipped out a group of packages on 31 of January, I checked them on the app later, and all of them had been “accepted at USPS” facility that same night except for one. It’s now been 4 days and all my other packages have been delivered. Except for that one and it still says it needs to be shipped. What do I do?