There is a session ID that is not being returned in the request header in 'Live' Mode however is returned in 'Test' Mode?

The reason the issue occurred was due to the introduction of a new http cookie attribute in browsers. This attribute, when set with certain values, can restrict whether cookies can be accepted across different domains. When making EFT or Credit card payments, the process requires redirects between your website and Adumo Online. The problem is when this new attribute restricts your website session cookie from being sent in a first-party context. This results in users being logged out when Adumo Online redirects back to your website without the session cookie in the request header. We are certain it is not a framework update but rather suspect that it is due to certain browsers having been updated with this change over the December period.

The fix is simply disabling this attribute from taking effect.

If you experience this- Please look at these below links:

https://stackoverflow.com/questions/59117357/how-samesite-attribute-added-to-my-asp-net-sessionid-cookie-automatically

https://stackoverflow.com/questions/59269476/browser-wont-set-asp-net-sessionid-cookie-on-payment-gateways-post-request-to