Shipping Classes/USPS Rate Calculation No Longer Functioning

Hi, I’ve been trying to solve some general server problems concerning my website – was getting plenty of errors when trying to work inside wordpress. Eventually I switched from PHP 7.2 CGI to PHP 7.2 FastCGI and this seems to have solved a lot of my issues. At some point while doing this, Woocommerce Services appears to have bugged out on Shipping Classes. I use these to determine if an order is available to send via Media Mail because it only contains books, or if the order needs to be sent through First Class or Priority Mail because it contains merchandise. The area below “Shipping Classes” on the Shipping Zone Methods individual pages is now blank, but sort of flashes a “yes” or “no” if I click near it. This seems to have caused, or at least coincide with accidentally, a complete failure of being able to retrieve shipping calculations from USPS, and now my cart will only display the fallback price relevant to the items in the cart. And even then – sometimes, it does not give any price whatsoever and would allow checkout through paypal with no shipping added on at all. The final result is a pretty severe problem that I need rectified. I can’t operate a shop with having it not add in shipping costs whatsoever.

The page I need help with: [log in to see the link]