We're using Magento version 1.9.0.1 to house multiple websites/stores (setup via API). Recently, we noticed that some of the newly added stores does not display USPS in the shopping cart even though all of them follow the same configuration. Products have been verified to have the weight value entered. Toggled on/off other shipping methods, e.g. UPS, and they worked fine. Cache had been cleared and deleted as well. Logs do not indicate any issue pertaining to shipping methods.
What else could we check?
USPS Setting:
Found the issue. We have a separate database that contains store information including ship-from address. Affected stores have country set to 'United States of America' while the rest have plain 'US'. Updated the value to 'US' for all stores and that fixed it.