tooltip not showing first data point in a smooth line graph

When hovering the cursor over the beginning of a line in a smooth line chart in order for the tooltip to display the value for the line at that point, the value for the second data point is displayed, and not the first data point.

When changing the chart type to a straight line chart and doing the above, the value for the first data point is displayed.

Is there a way to have the tooltip display the value for the first data point in a smooth line chart when hovering the cursor over the beginning of the line?

In case it helps, below is the expression code for the tooltip.

Thanks for your assistance.

=Fields!rsrc_1.Value & " " & Sum(Round(Fields!unit_1.Value)) & " MWh - " &
 DateAdd("h", (Fields!ct_hr.Value - 1), Fields!ct_dt.Value )