Hello Ben,

I reproduced the described behavior and used the provided code on my machine. To achieve the desired result, there are two options:

• Intermediate additional filtration - this is necessary because the Equals method works with references. In your case, to achieve that, all you need to do is add the below code block to the TreeListExample.razor.cs file starting from row 58.
  

  var expandedIds = localStorage.ExpandedItems.Select(x => x.Id);
  var expandedItems = TreeListItems.Where(x => expandedIds.Contains(x.Id)).ToList();
  localStorage.ExpandedItems = expandedItems;
  args.TreeListState = localStorage;

• Overriding the Equals method - thus you will be able to avoid the reference comparison.

In the attached file, I have used the first way. There you can see the example you provided with the added required lines of code in the TreeListExample.razor.cs.

In the meantime, I am marking the portal status of this thread as "Declined" since the described behavior is not an actual bug and the desired result could be achieved with the current setup of the component, using one of the above-mentioned approaches.

I hope this helps and if you have any other questions, let me know.

Regards,
Hristian Stefanov
Progress Telerik