[Emergent Help]Stamps.com did not work out on USPS First Class shipping labels and in

Dear representative,
I use ShipRush for Stamps.com to print the shipping labels, and today I found I could print the label in the software (I mean there is no error message when I click to print), but the shipping labels did not come out from the label machine and also I found the tracking number cannot be upload to USPS server, because I could not find the tracking information from USPS.com (Usually, when I printed a shipping label via ShipRush for Stamps.com, it will generate a tracking number, and immediately this tracking number would be received by USPS server, and I can verify that from USPS.com, the search resuld would show "Electronic Shipping Info Received"). But each shipping label was charged sucessfully.

In total, I have this issue for 13 orders, which all used the USPS First Class service with tracking number. I will give you two examples here:
1)9400111899560271824845
2)9400111899560271824494

As you can check from USPS.com, it did not uploaded to USPS server, and

This is the first time I met this issue, and cannot find the exact reason. Then I need your help emergently, because I have to ship out the orders as soon as possible.

Thank you very much in advance.
Best Regards