GraphQL updateIssue does not seem to work

I have been trying to perform the updateIssue mutation, the but I don’t think its working, the response is 200 but fields I want to update were not updated, in this case issue title-

mutation ($issue_id: ID!){
  updateIssue(input: {id: $issue_id, title: "FIRST GOOD ISSUE updated"}) {
    issue {
      number
      id
      repository {
        nameWithOwner
      }
      title
    }
  }
}