public void LoadData() { CategoryItems = System.Threading.Tasks.Task.Run(() => GetCategoryItems()).Result; CategoryTasks = System.Threading.Tasks.Task.Run(() => GetCategoryTasks()).Result; ItemList = System.Threading.Tasks.Task.Run(() => GetItems()).Result; ItemList = new ObservableCollection <Item>(ItemList.Where(e => !CategoryItems.Contains(e)).ToList()); TaskList = System.Threading.Tasks.Task.Run(() => GetTasks()).Result; TaskList = new ObservableCollection <Model.Task>(TaskList.Where(e => !CategoryTasks.Contains(e)).ToList()); }