When applying multi-level grouping, then change the items group keys, the new groups are added but the old ones are still visible in the list view, and from child group they become parent group. 

Workaround:

clear the group descriptors before changing the items and then re-add the group descriptors again

This is from our production app. Cannot reproduce it, don't know exactly when or why it happens; we just have crashes logged to have happened to 9 users in the past year with a total of 30 occurences.

These are unhandled UWP exceptions, which mean that our app goes poof :)

System.ArgumentException: Value does not fall within the expected range at
System.ThrowHelper.ThrowAddingDuplicateWithKeyArgumentException(Object) + 0xf     at
Telerik.UI.Xaml.Controls.Data.ListView.Model.BaseLayoutStrategy.RecycleLocally() + 0x320     at Telerik.UI.Xaml.Controls.Data.ListView.Model.BaseLayoutStrategy.MeasureContent(RadSize, Double, Double) + 0xd     at Telerik.UI.Xaml.Controls.Data.ListView.Model.LayoutController.MeasureVertical(RadSize) + 0x1b9     at Telerik.UI.Xaml.Controls.Data.ListView.Model.LayoutController.MeasureContent(RadSize) + 0x42     at Telerik.UI.Xaml.Controls.Data.ListViewModel.MeasureContent(RadSize) + 0x2e     at Telerik.UI.Xaml.Controls.Data.RadListView.OnContentPanelMeasure(RadSize) + 0x17f     at Telerik.UI.Xaml.Controls.Data.ListView.ListViewPanel.MeasureOverride(Size) + 0x60     at Windows.UI.Xaml.FrameworkElement.global::Windows.UI.Xaml.IFrameworkElementOverrides.MeasureOverride(Size) + 0x26

System.ArgumentException: An item with the same key has already been added    at
System.ThrowHelper.ThrowAddingDuplicateWithKeyArgumentException(Object) + 0xf     at Telerik.UI.Xaml.Controls.Data.ListView.Model.BaseLayoutStrategy.RecycleLocally() + 0x320     at Telerik.UI.Xaml.Controls.Data.ListView.Model.BaseLayoutStrategy.MeasureContent(RadSize, Double, Double) + 0xd     at Telerik.UI.Xaml.Controls.Data.ListView.Model.LayoutController.MeasureVertical(RadSize) + 0x1b9     at Telerik.UI.Xaml.Controls.Data.ListView.Model.LayoutController.MeasureContent(RadSize) + 0x42     at Telerik.UI.Xaml.Controls.Data.ListViewModel.MeasureContent(RadSize) + 0x2e     at Telerik.UI.Xaml.Controls.Data.RadListView.OnContentPanelMeasure(RadSize) + 0x17f     at Telerik.UI.Xaml.Controls.Data.ListView.ListViewPanel.MeasureOverride(Size) + 0x60     at Windows.UI.Xaml.FrameworkElement.global::Windows.UI.Xaml.IFrameworkElementOverrides.MeasureOverride(Size) + 0x26

when we try to add a dynamic AutomationId in each item of the list (something like AutomationId="{Binding Id}"), the AutomationId is not provided to the elements we see in the appium inspector. 

Works with fixed values

Telerik RadListView with two Columns - they are Thumbnails with a tap gesture. When we change the Spancount to 1 there is no right border line but when set back to 2 it shows as the screenshot on IOS, 

The issue happens on iPhone 11, XR, devices with a notch, and when ListViewGridLayout is with SpanCount="2".

Workaround: Set the background color of the ListViewItemStyle to Transparent

<telerikDataControls:RadListView.ItemStyle>
    <telerikListView:ListViewItemStyle BorderWidth="0" 
                                        BackgroundColor="Transparent"/>
</telerikDataControls:RadListView.ItemStyle>

After I updated to `2021.1216.1-hotfix` (to solve this problem in Android and Google Material) the RadListView's LoadOnDemand automatic  stopped working 

Workaround:

I've had to downgrade Xamarin.Google.Android.Material to v1.1.0.5 and use the latest stable release of Telerik UI v2021.1.119.1 which restored the functionality.

Hello, could you provide some guidance about the following situation....

I have a scenario using the RadListView that implements a PropertyGroupDescriptor for a property attached to my ObservableCollection<T>, where the property that it is monitoring is string value.  The dataset is designed that it may have only one grouping before an item is selected them the dataset will have two different groupings.  One the data changes, the ListView updates to show that there are two different groups but the group header doesn't change and neither does the cell content.  If I click on the GroupHeader of the new section, then it updates to reflect the change in data.  Is there a way to get the data to change in the Listview with some kind of Refresh so it stays up to date with the data.

Seeing it on iOS right now.

Thanks

When an item in the ItemsSource of a ListView is null, a NullReferenceException will be raised on Android when the items source is loaded to the list view.  Even if a DataTemplateSelector is applied to display a different datatemplate for null items, the app would still crash.

I attached a sample program that demonstrates the issue.  On iOS the app runs fine, but on Android the app crash at launch with a NullReferenceException.

Thanks,
Kori

Changing a property on an item that is involved with grouping and sorting and then removing and re-adding the item to the collection results in the list being in an invalid state (e.g. duplicate items, incorrect template, etc.)

Error message can be reproduced on iPhone 11 Simulator iOS 13.6 

[UICollectionView] Invalid update: invalid number of items in section 0.  The number of items contained in an existing section after the update (4) must be equal to the number of items contained in that section before the update (4), plus or minus the number of items inserted or deleted from that section (1 inserted, 0 deleted) and plus or minus the number of items moved into or out of that section (0 moved in, 0 moved out). - will perform reloadData. UICollectionView instance: <TKCollectionView: 0x7f8525b86600; baseClass = UICollectionView; frame = (0 0; 414 725); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x600001232bb0>; layer = <CALayer: 0x6000019b0520>; contentOffset: {0, 0}; contentSize: {414, 453}; adjustedContentInset: {0, 0, 0, 0}; layout: <TKListViewLinearLayout: 0x7f8524f5e400>; dataSource: <Telerik_XamarinForms_DataControlsRenderer_iOS_TKExtendedListView: 0x7f8524f5b590; frame = (0 0; 414 725); layer =
 <CALayer: 0x6000019b03a0>>>; currentUpdate: [UICollectionViewUpdate - 0x7f8526897fc0: old:<UICollectionViewData: 0x6000025f4000> new<UICollectionViewData: 0x6000025f47e0> items:<(
    "I(0,3)"
)>]

Hello,

I receive often a NullReferenceException in ListViewGroupHeader ArrangeOverride method.

The error happens only in UWP.

Unfortunately, I cannot create a project to reproduce the error.

Best regards,