I am using treeview loadondemand, doing an api call for every node that I open. I noticed that when I tried to open an item with 33 children object, it hangs the application.

The issue occurs when TreeViewItemTemplate is used.

Without the itemtemplate no issues.

Above the TreeView there is a Telerik.SegmentedControl, with two segments. If I click on one of the segments the ItemsSource of the TreeView gets updated by using .Add() or Remove() of the ObservableCollection.

If every Segment is called for the first time there is no problem. But if I want to clear all Items and display the empty treeView I get the following Exception.
Java.Lang.IndexOutOfBoundsException: 'Inconsistency detected. Invalid item position 0(offset:-1).state:14 md5a5af569a83c1a3f5c3a8a63bd7d39860.RadExtendedListView{c6376f1 VFED..... ........ 0,0-1200,840 #5}, adapter:com.telerik.widget.list.ListViewWrapperAdapter@b30041b, layout:android.support.v7.widget.LinearLayoutManager@3fd42d6, context:md5db22775bb305bf9756607f4261793d51.MainActivity@1d6cd4f

If items are loaded on demand and treeview is placed inside StackLayout, when collapsing and expanding items, at some point the rendering is messed up.

When you have longer text shown in TreeView items and it is wrapped in 2 or 3 rows, the text is clipped incorrectly.

Currently if the TreeView has deeper hierarchy or items with longer text, the end user will not be able to scroll horizontally.

When we remove the last item from the observable collection we get an unhandled exception like this:

"Attempt to delete item 0 from section 0 which only contains 0 items before the update"

When you have custom ItemTemplates defined with different height, scrolling up through the items causes flickering, also you cannot scroll down to display all the items.

When using MvvmCross framework to load data when the View appears on the screen the ListView cannot be scrolled. It starts jumping rapidly instead.

Workaround:
Load the data in the constructor of the respective ViewModel instead inside its ViewAppearing() method.

when custom renderer is registered, it is not applied to the TreeView control. The default one overrides the custom one.

When the custom ItemTemplate sets bigger value of its Height e.g. more than 44 pixels, the content of the UITreeViewCell is not sized correctly. Only the cell gets the correct value.

When there is custom template applied that hosts multiple rows of UI components with total height greater than 44, the template is not measured correctly, leading to wrong visualization.

When TreeView has a source with more than 120 items and is placed inside a StackLayout, it is not properly rendered (Layout Cycle Detected exception is raised).

When the collection set as ItemsSource of the TreeView is cleared and new item is added, an exception of type NSInternalInconsistencyException is raised on iOS.
Also clearing the ItemsSource is not reflected in TreeView.

If the control is not yet visualized on the screen and the method is invoked an exception is thrown.

When we have grouping enabled and 2 properties with same name (i.e. TestId and TestID), the ListView is not rendering (or at least not showing any records)

Trying to collapse an item after reinitialization of the RadTreeView causes the exception. The scenario can easily be recreated if all items from the ItemsSource are removed one by one and then added again then expand and collapse an item.

Calling TreeView's CheckItem method when the control is loaded, so that you mimic a "pre-checked" TreeView results in NullReferenceException in RadTreeView.Checkbox ToggleItem method.

When CollapseAll method is called, if the first element is out of the screen (after a scroll), the treeview crashes.

Available in minor release 2018.3.1109. It will also be available in the R1 2019 release.

Available in R3 2018 release.

Expose a BringIntoView or ScrollIntoView method that would scroll the TreeView to a specified TreeViewItem.

Available in R3 2018 release.  For more details on the feature refer to: https://docs.telerik.com/devtools/xamarin/controls/treeview/treeview-scrolling