Accounts.createUser callback not called in mobile device only

help
1 
Accounts.createUser({
  email: email,
  password: password
}, function (err) {
  console.log("inside createUser callback");
  if (err) {
    console.log("createUser failed", err);
    return false;
  }
  console.log("callback inside createUser");
  IonModal.close();
});

I am developing an ios app with Meteor (and Meteor Ionic), and I am stuck at a weird point. The callback for createUser only seems to be called when I test on my browser. In my iOS device, everything works except the callback. I don’t see any error message.

Does anyone have an idea or have had a similar problem?