API Endpoint Error: ‘Missing parameter: grant_type’ Despite Parameter Being Specified

I’m encountering a “missing parameter: grant_type” error during authentication, despite including it as a query parameter (shown in the screenshot above). This issue occurs both in Postman and via the API Reference website.

I’ve successfully used the “Get Authorization Code” endpoint and pasted the received code correctly. Could this be an internal issue, or is there something I’m overlooking?