Wijmo 5 [Flex Grid]

Group Panel wj-groupmarker don't go away when X button click

HTML

<link rel="stylesheet" href="http://cdn.wijmo.com/5.20162.188/styles/wijmo.min.css">
<script src="http://cdn.wijmo.com/5.20162.188/controls/wijmo.min.js"></script>
<script src="http://cdn.wijmo.com/5.20162.188/controls/wijmo.input.min.js"></script>
<script src="http://cdn.wijmo.com/5.20162.188/controls/wijmo.grid.min.js"></script>
<script src="http://cdn.wijmo.com/5.20162.188/controls/wijmo.grid.grouppanel.min.js"></script>
<script src="http://cdn.wijmo.com/5.20162.188/interop/angular/wijmo.angular.min.js"></script>
  <div ng-app="app" ng-controller="appCtrl">
        <wj-group-panel grid="flex"
                        placeholder="Drag columns here to create Groups"
                        max-groups="4">
        </wj-group-panel>
        <wj-flex-grid control="flex"
                      items-source="data">
        </wj-flex-grid>
    </div>

JavaScript

var countries = 'US,Germany,UK,Japan,Italy,Greece'.split(',');
        var data = [];
        for (var i = 0; i < 50; i++) {
            data.push({
                id: i,
                country: countries[i % countries.length],
                date: new Date(2014, i % 12, i % 28),
                amount: Math.random() * 10000,
                active: i % 4 === 0
            });
        }
        var app = angular.module('app', ['wj']);
        app.controller('appCtrl', function ($scope) {
            $scope.data = new wijmo.collections.CollectionView(data);
        });