Angular-styleguide: Arrays under scope.vm of directive undefined

Greetings,

When following Angular 1.x style guide for directives, if I am referencing the array scope.vm.virtStats from the controller, it comes back as undefined. but if I reference simple object from the controller such as scope.vm.title, it does return a value. Why is that? Because I do see scope.vm as having that virtStats
array in the console.

        .module('app.dashboard')
        .controller('Dashboard', Dashboard)
        .directive('d3Chart', buildChart);
       `function buildChart() {
            var directive = {
                restrict: 'EA',
                link: linkFunc,
            };

            return directive;

            function linkFunc(scope, el, attr, ctrl) {
            ...lots of d3 visualization code here
                console.log(scope.vm)
            }


function Dashboard($state, $scope, dataservice, logger) {
        var vm = this;
        vm.virtStats = [];

        vm.title = 'Dashboard';

        clearSearchResult();

        activateVirtsData();

        function clearSearchResult() {
             vm.virtStats = [];
        };


        function activateVirtsData() {
            return dataservice.getVirtStatsData().then(function (data) {
                vm.virtStats = data;
                return vm.virtStats;
            });     
        } );            
        };