When generating an access token as a JWT, the preferred_username claim is missing or blank,
This occurs because the preferred_username claim is only set when a scope of openid is requested.
Release : 9.4
Component : API GATEWAY
To return the username you will need to ensure that the client is registered with and requests the scope of openid.
Optionally, the scope check can be removed or customized to another scope value defined in your organization.