Dart Throws No 'Access-Control-Allow-Origin' header error even though it is there

Question

I have a basic go API server that serves up a "job" from the database and returns in in a JSON response with the Access-Control-Allow-Origin: * added to the header.

func GetJob(w http.ResponseWriter, r *http.Request) {

job := Job{}

db, err = gorm.Open("postgres", connString)
if err != nil {
    panic("Could not connect to the database")
}
defer db.Close()

vars := mux.Vars(r)
jobID, err := strconv.Atoi(vars["jobid"])
if err != nil {
    panic("can't convert string")
}

db.Debug().Where("id = ?", jobID).First(&job)

w.Header().Set("Access-Control-Allow-Origin", "*")

json.NewEncoder(w).Encode(&job)

}

This is intended to be read my a client app written in angular dart:

class DataService {
final _headers = {'Content-Type': 'text/plain'};
var jobUrl = 'http://127.0.0.1:9000/job';

final Client _http;
DataService(this._http);


Future<Job> getJob(int id) async {

  try{
  final response = await _http.get('$jobUrl/$id/');
  return new Job.fromJson(_extractData(response));
 }
 catch (e) {
   throw _handleError(e);}
}

On postman I can access it with no issues with the Access-Control-Allow-Origin header also. However, when I call the getJob(1) function from the app, chrome throws an error:

XMLHttpRequest cannot load http://127.0.0.1:9000/job/1/. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8080' is therefore not allowed access.

Any ideas on what I am missing here? Most likely everything.