GraphQL query not returning data
The answer is to filter by content type:

{
  nodeQuery(
    filter: {
      conditions:[
        {operator: IN, field: "type", value: ["global_content"]},
      ]
    }
  ) {
    entities {
      ...on NodeGlobalContent {
        title
        body {
          value
        }
      }
    }
  }
}