public void InitDataGrid()
{
// [Grid 속성]
{
this.xDataGrid.HeaderHeight = 50;
this.xDataGrid.AutoGenerateColumns = false;
this.xDataGrid.DefaultColumnMinWidth = 100;
this.xDataGrid.HeaderClickAction = HeaderClickAction.SortByOneColumnOnly;
this.xDataGrid.RowHeight = 50;
this.xDataGrid.RowSelectionAnimationMode = RowSelectionAnimationMode.ColorBlend;
this.xDataGrid.RowSeparatorHeight = 2;
this.xDataGrid.SelectionMode = GridSelectionMode.SingleRow;
}

//this.m_DataGrid.SelectedItemsChanged += Grid_SelectedItemsChanged;
this.xDataGrid.CellClicked += delegate (object sender, GridCellEventArgs args)
{
AudioPlayer.PlayClickSound();
args.Grid.SortDescriptions.Clear();
};

ClearDataGrid();
this.xDataGrid.ItemsSource = this.m_Model.SpectrumMeasureData;
}

public void ClearDataGrid()
{
// [Grid Headr 초기 세팅]
this.xDataGrid.Columns.Clear();
this.m_Model.SpectrumMeasureData.Clear();

// [Wave header 생성]
Column Wavelength = GridUtil.Instance.SetColumn(ColumnTypes.Text, "Wave", "Wavelength", new ColumnWidth() { Value = 150 });
this.xDataGrid.Columns.Add(Wavelength);

// [파장값 입력]
this.m_Model.InitMeasureSetup();
foreach (var wave in this.m_Model.WaveList)
{
SpectrumMeasureData Data = new SpectrumMeasureData();
Data.Wave = wave;
this.m_Model.SpectrumMeasureData.Add(Data);
}

// [차트 x축 초기화]
this.xDataChart.Series.Clear();
NumericXAxis xaxis = (NumericXAxis)this.xDataChart.Axes.FirstOrDefault(x => x is NumericXAxis);
xaxis.MinimumValue = this.m_Model.StartWave;
xaxis.MaximumValue = this.m_Model.EndWave;
xaxis.UpdateRange(true);
xaxis.ScrollRangeIntoView(xaxis.MinimumValue, xaxis.MaximumValue);

// [차트 y축 초기화]
NumericYAxis yaxis = (NumericYAxis)this.xDataChart.Axes.FirstOrDefault(x => x is NumericYAxis);
yaxis.MinimumValue = -5;
yaxis.MaximumValue = 5;
yaxis.UpdateRange(true);
yaxis.ScrollRangeIntoView(yaxis.MinimumValue, yaxis.MaximumValue);

this.xDataGrid.ScrollToColumnByIndex(0);
//this.xDataGrid.ItemsSource = this.m_Model.SpectrumMeasureData;
}

public class SpectrumMeasureData
{
public float Wave { get; set; }
public List<float> ABS
{
get; set;
} = new List<float>();

}

I put 10 grids in the beginning.
Then, call the ClearDataGrid() function and call the this.m_Model.SpectrumMeasureData.Add(Data); function to insert 5. In this case, ArgumentOutOfRangeException is thrown. It cannot be traced to the callstack.