If the site is behind Cloudlflare, please add a rule to allow all INICIS IP address and requests, you can do this by adding a rule for KG INICIS ASN.
ASN: AS9571 – ALLOW ALL
“clientASNDescription”: “INICIS-AS INICIS Co., Ltd”,
Magento Cloud WAF
When making a payment request you find a 404 page as below, this usually means Magento Web Application Firewall rule needs updating to allow
the INICIS return url request, please see below from magneto doc, and submit a ticket to Magneto support.