Firebase Realtime Database Raw Mode timeout

When I hit preview on a query to a Firebase Realtime Database in Raw Mode it just times out after a few mins.

This is the code I run

var ref = db.database().ref("temp/news/newsItems");
var snapshot = await ( ref.once("value"));
return snapshot.val();

I can get access to the data normally outside of raw mode so the permissions are ok. I would like to use Raw mode because I am finding it hard to do things in GUI mode.

If anyone has any experience of using realtime DB I would really like some help.