To reproduce: the issue is reproducible in the Demo application >> GridView >> Tabbed Views. Follow the steps from the gif file.

Workaround:     
    private void radGridView1_ViewCellFormatting(object sender, CellFormattingEventArgs e)
        {
            GridDetailViewCellElement cell = e.CellElement as GridDetailViewCellElement;
            if (cell != null)
            {
                cell.MinSize = new Size(e.CellElement.Parent.Size.Width - this.radGridView1.TableElement.GroupIndent , 10);
            }
        }