With our official release we have applied several optimizations and new features. The problem with the mentioned project is that you are adding a GroupDescription
for a property which does not exist (the PropertyName
is set to  for example, but in fact such property doesn't exist). But there is solution for your problem - RadPivotGrid
, so you can add properties dynamically. This way you can add the property  at runtime and use it. When it is not needed anymore, you can remove it. RadPivotGrid
will have no problem to handle such operations. I'm sending you the modified version of the project. Please note that there's no need to use custom FieldDescriptionProvider
Could you check the attachment and inform us if you have any problems or concerns.
the Telerik team