I am having a save issue with my property editor prevalue. I have the following prevalue:

            prevalues: {
            fields: [
                {
                    label: "Indexes",
                    description: "Index to search on",
                    key: "index",
                    view: "~/App_Plugins/Similarity/views/indexes.html",
                    validation: [
                        {
                            type: "Required" 
                        }                       
                    ]
                }

My view looks like

<div class="umb-editor umb-checkboxlist" ng-controller="similarity.indexController">
    <div>           
        <select ng-model="model.config.index" class="umb-editor umb-dropdown" ng-options="o for o in indexes">              
        </select>
    </div>

and my controller looks like

angular.module("umbraco").controller("similarity.indexController",
    function ($scope, indexResource) {

        //get the indexes from /umbraco/backoffice/api/SimilarityApi/GetIndexes
        indexResource.getAllIndexes().then(function(response){

            $scope.indexes= response.data;

        })
    });

The prevalue stuff all loads fine my drop down is populated and I can select a value however when I save it does save however it does not restore the picked value. I am missing something obvious, any ideas?

Regards

Ismail