Angular $scope variable is not updating after processing data via angular service

I'm developing an AngularJs application that fetches via Angular Resource.

I receive the array of data just fine, and view the records inside a table view via ng-repeat and everything works great.

The problem is that, when I process my array of data using underscore.js inside my service, ng-repeat gets an empty array. Despite that if I log the same scope variable after the the processing, I get the result as expected.

My Angular Service code:

app.factory("DataProcessor", function() {
    return {
        ToAssocArray: function(input) {
            retData = [];
            _.each(input.data, function(elmnt, i, list) {
                retData[elmnt.id] = elmnt;
            });
            return retData;
        }
    };
});

Code snippet from my controller:

app.controller("main_ctrl", function($scope, $timeout, Data, DataProcessor) {
...

    $scope.serverData = [];
    $scope.myData = [];
    $scope.myDataProcessed = [];

    $scope.serverData = Data.query({});
    $scope.serverData.$promise.then(
        function onSuccess(result) {
            $scope.myData = result; // here I receive the data just fine.

            $scope.myDataProcessed = DataProcessor.ToAssocArray(result); // my data processing
            console.log($scope.myDataProcessed); // processed data gets logged flawlessly
        },
    );

And inside my html when I type:

{{myDataProcessed}}

I get:

[]