Async variable stored in $rootScope not available in other controllers

I am using Angular 1.x for my stack and when I make an API call and store the response in the $rootScope, it is not accessible in other controllers' view.

My controller:

angularApp.controller('mainController', ['$scope', '$rootScope', '$http', function($scope, $rootScope, $http){

  var checkIfAuthenticated = function(){
    return $http.get('/api/isAuthenticated');
  };

  checkIfAuthenticated()
  .then(function(res) {
    if(res.status===200){
        console.log("Success");
        $rootScope.userLoggedIn = true;
    } 
  })
}]);

Now, in another controller's view I use it like this:

<div ng-if="userLoggedIn" class="py-1 pl-1 pr-1">
  <span><b>Message Board</b></span>
  <div class="form-control" readonly id="lockTextbox">Show something</div>
</div>

The problem is, the API call /api/isAuthenticated does provide the right response (status 200) but the ng-view gets it wrong.

I am sure this is to do with $rootScope.userLoggedIn being a response from an async call (as I get Success in my console) but how do I solve it?

Thanks in advance!

EDIT

After I posted the question, I noticed that in the mainController's view, the ng-if logic doesn't work either. What is very strange is that when I open up the browser's debug console, it starts working! I think this is just an async issue but I don't know how to solve it. How do I tell the view that the variable is on it's way?

I found the problem. I updated my Angular from 1.6.4 to 1.7.9 (and all modules like angular-sanitize etc) and that did the trick. Should have been the first thing I did but I missed it entirely