WpgraphQL Viewer query always returns null

Question

I am working on a headless WordPress + Next.js app

In my GraphiQL ide when i query the current viewer (me !) I keep getting null as a result

I am using the latest WP version + latest wpgraphqQL + latest WPGraphQL CORS plugin

May be this is caused by the fact that for the moment my WordPress installation is in local but i tried to add wpgraphQL on another website in production and to reproduce this and I still get this null for my current Viewer

Don't know if this issue is linked to wpgraphQL or me

Thanks for any help

Here is my query

query MyQuery {
  viewer {
    name
    username
  }
}