Here is a workaround for this issue provided by Infragistics:
private void ultraChart1_FillSceneGraph(object sender, Infragistics.UltraChart.Shared.Events.FillSceneGraphEventArgs e)
IAdvanceAxis y = e.Grid["Y"] as IAdvanceAxis;
if (y != null)
this.ultraChart1.Axis.Y.RangeMin = 0;
this.ultraChart1.Axis.Y.RangeMax = (double)y.Maximum;
this.ultraChart1.Axis.Y.RangeType = AxisRangeType.Custom;
The only problem with it is that works only with NetAdvantage 7.3 or newer, because starting with this release Infragistics provides the FillSceneGraph event which is used.