When a value is modified in code, the items displayed in RadGridView are not updated according to defined SortDescroptors, FilterDescriptors or GroupDescriptors.
The reason for this behavior is that a CollectionChanged event of the bound source collection is not raised.
In order to get the items refreshed, you have to notify the GridView that the bound collection has been changed. A CollectionChanged notification of the bound collection should be raised.
There are four possible solutions:
You can update the value as illustrated in the Edit items outside RadGridView article.
Invoke RadGridView.Rebind() method. It will raise CollectionChanged notification with action Reset. Please note that the entire view will be recreated.
Ensure that CollectionChanged event is raised from the bound source collection.
When a nested property is modified and a notification is raised for it as suggested in point 1., then RadGridView will not receive it and the data displayed will not be re-evaluated. In that case the suggested solutuons listed as 2. or 3. should be applied.
You can also find the blog post on Fast real-time update.