USPS Priority has stopped working on our site. It is selected in Shipping settings and neither the "Test USPS Rate" dialogue, nor our site will display rates for Priority.
This appears to be related to the recent USPS API changes documented on their site: https://www.usps.com/business/web-tools-apis/welcome.htm I have a hard time believing I am the first one to bring this up though :/
Reviewing order history I see that the last Priority Mail we shipped was 2 days before USPS pulled the switcharoo.
The first thing to try in this case would be resetting the USPS credentials by deactivating and reactivating the account.
This will pull new information and reset the rates we are offering with the correct information.
The USPS recently simplified the product names for Priority Mail to Priority 1-day (Priority 2-day & 3-day) - check out this link below for more information about the changes.