API Gateway - error trying to validate JWT

Summary

API Gateway throwing an error when trying to validate a JWT token from IDCS - Token authorization scheme could not be determined

Content

Hi,

I have a POC, trying to secure an API configured in API Gateway with JWT. We are using IDCS to provide the access token. The API through the gateway works without security. There is no front-end yet, I'm using Postman.

I'm doing this so far:
1. Create user assertion with jwt.io
2. Use Postman to ask IDCS for a token
3. Use Postman again, make a request to the Gateway with the token (fails with 400 Bad Request)