To reproduce: bind the grid to self reference data source, and on a button click, Fill the TableAdapter

Workaround: clear the relations to clear the cache and add them back after the adapter is filled:
RadGridView1.Relations.Clear()
        Me.Table1TableAdapter.Fill(Me.Database8DataSet.Table1)
        Me.RadGridView1.Relations.AddSelfReference(Me.RadGridView1.MasterTemplate, "TaskID", "ParentTask")