Xamarin表单Listview - 更新ObservableRangeCollection时UI不会更新

Question

我有一个包含多个数据模板的列表视图。其中一个模板是简单的文本框和条形码扫描按钮（ZXingLibrary）。列表视图的页面以模态显示。该页面显示一个问题，其中包含绑定到列表视图的响应列表。条形码类型模板就是这样一种反应。

我正在更新以下代码中绑定到listview的可观察范围集合。成功完成条形码扫描后调用此功能。

private void UpdateUserResponseList(UserResponse obs, string result)
    {
        var temp = obs;
        obs.RValue = result;
        ObsList.Remove(temp);
        ObsList.Add(obs);
     }

当UI刷新时，两个平台中的listitem索引都会发生变化。这在iOS中完美运行。但是在Android中，只有当ObsList的计数大于1时才会刷新UI。它会保存集合中的值，但不会在文本框中显示/更新。

的ListView

 <ListView x:Name="ObsListView" IsVisible="{Binding IsObservations}" CachingStrategy="RecycleElement" Margin="20" ItemsSource="{Binding ObsList}" SeparatorVisibility="None" HasUnevenRows="true" BackgroundColor="Transparent" 
    ItemTemplate="{StaticResource ObservationDataEntrySelector}" />

ObservableRangeCollection

public ObservableRangeCollection<UserResponse> ObsList 
{ 
     get 
       { return _obsList; } 
     set 
       { 
          if (_obsList != value) 
          { 
             _obsList = value; 
             OnPropertyChanged("ObsList"); } } 
       }
 }

用户点击扫描条形码按钮时调用的功能

private void BarcodeScannerExecuted(UserResponse obj)
    {
        ZXingScannerPage scanPage = new ZXingScannerPage();
        var customOverlay = new StackLayout
        {
            HorizontalOptions = LayoutOptions.FillAndExpand,
            VerticalOptions = LayoutOptions.FillAndExpand

        };

        var Cancel_Button = new Button
        {
            Text = "Cancel",
            Command = CancelScanningCommand,
            HorizontalOptions = LayoutOptions.CenterAndExpand,

        };

        var Text_shown = new Label
        {
            Text = "Hold your device up to the barcode,Scanning will happen automatically",
            TextColor = Xamarin.Forms.Color.DarkRed,
            HorizontalOptions = LayoutOptions.CenterAndExpand,
            VerticalOptions = LayoutOptions.FillAndExpand

        };

        customOverlay.Children.Add(Cancel_Button);
        customOverlay.Children.Add(Text_shown);
        scanPage = new ZXingScannerPage(customOverlay: customOverlay);
        scanPage.OnScanResult += (result) =>
        {
            scanPage.IsScanning = false;
            Xamarin.Forms.Device.BeginInvokeOnMainThread(async () =>
            {
                UpdateUserResponseList(obj, result.Text);
                await _navigation.NavigatePopModalAsync();
            });
        };
        _navigation.NavigatePushModalAsync(scanPage);
    }