Apollo Studio | apollo-server | "Error: Unable to use introspection, make sure it is enabled" (but introspection is set to true)

Question

I've got Apollo Server properly serving my GraphQL API on http://localhost:4000. However, Apollo Studio is unable to properly see the underlying schema, despite introspection: true being set.

//index.ts
import { AppDataSource } from "./database/data-source"
import startApolloServer from './server'

AppDataSource.initialize()
    .then(async dataSource => {
        startApolloServer(dataSource)
    }).catch(error => console.log(error))

//server.ts
import 'dotenv/config'
import typeDefs from './graphql/typeDefs'
import resolvers from './graphql/resolvers';
import { ApolloServer } from 'apollo-server'

export default async function startApolloServer(AppDataSource) : Promise<void> {
    const server : ApolloServer = new ApolloServer({
        typeDefs, 
        resolvers,
        introspection: true,
        cors: {
            origin: '*',
            credentials: true 
        },       
        dataSources: () => {
            return {
                AppDataSource   
            }
        }
    });

    server.listen()
    .then( ({url}) => console.log(`\n 
    ********************************

    Apollo Server is ready at ${url}

    ********************************

    `))
}
```[enter image description here][1]


  [1]: https://i.stack.imgur.com/X7KO9.png