Samsung Wallet Web Checkout Integration Testing

I am currently working on integrating Samsung Pay and need to add a test card in Samsung Pay for testing purposes. I am following the guide provided here: Web Checkout v2 SDK: STAGE_WITHOUT_APK Guide | Samsung Developer.

However, after selecting a test card from the list, I encounter an error page and cannot proceed further. Upon debugging, I noticed that an API call using the service ID is returning the following error response:

{
“resultCode”: “500.1”,
“resultMessage”: “OPS: null”
}

Could anyone please advise on how to resolve this issue?