Authorization failed with "authorizationCode" security schema

[JohnnyBee]

Hello.
Problem is, after successfully logging in to the integrated developer portal I am trying to test my APIs by using the OpenAPI spec file. I get an error "Authorization failed" while I am trying to Authorize with "authorizationCode" security schema.
Everything works well with Drupal, as well as other types of security schemes.

Screenshot with error:

I managed to copy the link in the opened window for the authorization, it contains:

https://my-apigee-org.apigee.io/oauth_redirect?error=Invalid_request&error_description=Unsupported%2...