To reproduce:
List<PropertyStoreItem> propertyStoreItems = new List<PropertyStoreItem>();
propertyStoreItems.Add(modelItem);
RadPropertyStore store = new RadPropertyStore();
store.AddRange(propertyStoreItems);
Workaround:
Iterate the collection and use the Add method
foreach (var item in propertyStoreItems)
{
    store.Add(item);
}