javascript - 以编程方式更新可观察对象时，Knockoutjs不更新UI

当我以编程方式更新可观察对象并打开模态时，为什么下拉列表没有更新？这是所有代码 https://jsfiddle.net/krob636/jes9bvLw/119/

如果尝试先更改元素的值，则更改可观察值将更新下拉列表。单击启动模式按钮，然后单击可观察按钮。所选ID会更改，但下拉列表不会更改。现在单击“元素”按钮，然后再次单击“可观察”按钮。下拉列表确实发生了变化。

Java脚本

this.selectedSimulators = ko.observableArray().extend({notify: 'always'});

this.simulators = ko.observableArray([
  new Simulator(1, 1, 1, "CH-53E", "APT", "APT 2F190-2"),
  new Simulator(2, 1, 1, "CH-53E", "EAET", "EAET 2H164-2"),
  new Simulator(3, 1, 1, "CH-53E", "WST", "WST 2F174-2")
]);

this.openModal = function() {
  $('#exampleModal').modal('show');
  this.selectedSimulators(1);

  // UI does not update without calling this 
 //$("#ddSims").val(1);
}

的HTML

  <select class="form-control" id="ddSims" multiple="multiple" data-bind="options: simulators,
      optionsText: 'typeAndSerialNumber',
      optionsValue: 'id',
      selectedOptions: selectedSimulators,
      multiselect: {includeSelectAllOption: true}">
 </select>

 <button type="button" class="btn btn-primary" data-bind="event: {click: openModal}">
    Launch modal
  </button>