AngularJS: Include and scope inheritance = broken bindings?

In an attempt to clean up my partials I recently moved some of my global menus into seperate templates which I now include in the views which need them. As the menu (including a search bar) is global I have created a service which keeps track of the state of the menu and so on.

Problem is something funny happened after I started including.

HTML (Jade) of the View

div(ng-controller='HeroUnitCtrl', ng-include src='heroTemplate')
div(ng-controller='MainSearchBarCtrl', ng-include src='searchBarTemplate')

div.row-fluid
    div.span12
        table.table.table-striped.table-bordered
            tr
                th
                    a(ng-click='setOrder("id")') ID#
                th
                    a(ng-click='setOrder("client.name")') Kunde
                th
                    a(ng-click='setOrder("technician.name")') Tekniker
                th
                    a(ng-click='setOrder("createdAt")') Opprettet
                th
                    a(ng-click='setOrder("statusString")') Status

            tr(ng-repeat='record in records | orderBy:orderProp | filter:searchBar')
                td
                    a(ng-href='#/records/show/{{record.id}}') {{record.id}}
                td {{record.client.name}}
                td {{record.technician.name}}
                td {{record.createdAt}}
                td {{record.statusString}}

HTML (Jade) searchBarTemplate

input#searchField.input-xxlarge(type='text', placeholder='placeholder', ng-change='searchBarUpdated()', ng-model='searchBar')

Now to the bit I really don't understand,

MainSearchBarCtrl

function MainSearchBarCtrl(MainSearchBarService, $scope, $location) {
    $scope.searchBarTemplate = 'partials/main-searchbar';
    $scope.searchBar = 'Hello World!';

    $scope.searchBarUpdated = function() {
        console.log('Search bar update: ' + $scope.searchBar);
        MainSearchBarService.searchBarUpdated($scope.searchBar);
    }   
}

Initially the value of searchBar is as expected "Hello World". However, if I append any text it still only prints "Hello World". Or, if I replace the text it prints undefined. So it seems the binding is broken, but I don't really see why this is happening. Worth mentioning is that this wasn't case before I moved my search bar into a separate template.

Any help is greatly appreciated.