This question is essentially the same as
Can't Enabled Classroom API to project and I can't enable Classroom API to project
but there isn't a solution on either of these pages.
Our domain has been whitelisted to use the Classroom API (I have had email confirmation) but when I go to the developers console the API is not listed. If I use the wizard from the Google Developers Classroom API Quickstart Page I get 'The API you requested was not found. Dismiss' from within the console.
Does anyone know what is going on or what the solution is?
Many thanks, Peter