Issues Integrating Custom Membership Card System with Gateway Ticketing APIs

Hi everyone, I’m currently working on integrating a digital membership card system with Gateway Ticketing Systems APIs, and I’m facing an issue during the integration process. The same API flow works smoothly when using MembershipAnywhere digital membership card system, where member validation, status checks, and real-time responses are consistent and stable, but when I try to implement a custom-built membership card solution, I start seeing inconsistent API responses, occasional failures in syncing member data, and delays in real-time validation right after updates. From the API documentation perspective using Swagger, everything looks correct in terms of request/response structure and authentication, but the behavior in production is different compared to the third-party system. I suspect there might be some hidden dependencies like required headers, internal validation rules, caching/timing differences, or a specific request sequence that MembershipAnywhere handles internally but my custom implementation is missing. Has anyone experienced similar issues with Gateway Ticketing integration or seen differences between a working third-party solution and a custom build?