Have you tried this with the in-core 3-page checkout? I'm unclear as to what checkout process you're using, but I don't recognize a checkout page and I'm guessing that that's where you're running into problems:


[03-Feb-2023 15:50:04 America/New_York] Request URI: /invertersupply.com/index.php?main_page=checkout, IP address: 127.0.0.1