To reproduce:
- Set the position like this:
this.radChartView1.ChartElement.LegendElement.Alignment = ContentAlignment.TopCenter;

- Export the chart to an image, the position is not the same as in the application.

Workaround:
- Set the position manually:

this.radChartView1.ChartElement.LegendPosition = LegendPosition.Float;
this.radChartView1.ChartElement.LegendOffset = new Point(400, 0);