Local Graphiql CORS Error on Hydrogen Demo Store

I was going through the Hydrogen docs and installed the Hydrogen Demo Store. When I hit http://localhost:3000/graphiql I am getting an empty screen (plus the console errors below). When I visit http://localhost:3000 I get the Demo Store and have no issues.

Anyone with similar issues?

Access to script at 'https://unpkg.com/react@17/umd/react.development.js' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

GET https://unpkg.com/react@17/umd/react.development.js net::ERR_FAILED 520

index.es.js:826 Uncaught TypeError: Cannot read properties of undefined (reading '__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED')
at Object.r (index.es.js:826:15)
at 6856 (index.es.js:26809:4)
at i (bootstrap:19:32)
at 7139 (forEachState.es.js:14:38)
at i (bootstrap:19:32)
at 6676 (query.ts:103:2)
at i (bootstrap:19:32)
at startup:4:27
at startup:4:47

Uncaught ReferenceError: ReactDOM is not defined
at (index):39:7 

This issue suddenly fixed itself. Not sure why.