I have installed the Authentication API Debugger and tried with the login. I am able to see the redirected login page and able to successfully login. Once i login i could see the JWT opaque code and access token shows null.
Also, When i try to validate this opaque code with userinfo it is showing bad request.
Basically i wanted the user to login my web application and call the API end point with access token.
This is curious - You should be able to hit /userinfo with an opaque access token as well. Are you receiving an ID token in this flow? What happens if you also include the profile scope as welll?
Please see the following regarding the opaque access token: