I was looking into testing our access by generating a simple request to the Pilot environment, using a POST request to the “/cases” relative path (api-worldcheck.refinitiv.com/v2/cases ) and was getting a response back with the unauthorized 401 error. I transformed JS code from pre-request script from your postman collection into C# (sending script attached, and request body). Just FYI all Get requests work fine both from postman and azure apim, issue only for Post ones. Post requests also work from postman.
Please let me know if any other info is needed.