The OAuth integration for our system, including the GPT API, is encountering an issue where the GPT fails to call the token endpoint after correctly handling the Authorization process. This results in an error in the UI without any indication of the GPT hitting the token endpoint. When manually invoking the token endpoint using the generated code, the expected response, including the access token, is received through Postman. Additionally, sometimes the OAuth flow completes successfully when directly pasting the callback URL into the browser with the same code and state parameters.