Zend certified PHP/Magento developer

Fedex only populating roughly half of customers addresses USPS doesn’t at all

We’re having issues with customers trying to place orders. About half of them are getting errors saying that there’s no shipping method available for this address.. When they are properly written out, and confirmed without issue.
(We’ve checked them manually on google, fedex, and shipping easy)
Residential Delivery is enabled, and many of these addresses that are having issues, were working perfectly fine within bigcommerce and the native fedex module there.. So trying to figure out where to start looking.

We’ve reissued multiple keys for the USPS module and it doesn’t populate anything ever. Confirmed webservices addresses etc.. I’ve searched here some but seems most people having issues with fedex/usps are residential issues, we do have it enabled as mentioned above.