Thank you, it seems the .exe file in was blocked by my anti virus system. I run your solution and after adding an item of type ClubB, I am able to reproduce the issue.
Sorting and Filtering are data operations, they are actually done by building and executing a LINQ query over the source collection.
For example, when sorting on the Name property of the bound item, the generated query would be:
var result = viewSource.OrderBy(x => x.Name);
In your case the base class ClubBase do not have the respective properties (Name, Established and
StadiumCapacity) and that is why we cannot build and execute a query based on those properties over the list of ClubBase objects. That is why there is no filtering icon shown and the sorting and grouping are also not working
When all the items are of type ClubA, then RadGridView is smart enough to take ClubA as type of the items instead of ClubBase. When there are different type of items though, we cannot do so as we do not know which type to get.
You need to design your data so that you to be able to build and execute such a query.
Then, you can also specify the ItemType explicitly:
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