I analyzed your code (thank you by the way).

It seems I am doing everything right...

Here's a chunk of my code:

public void setChartAppearance(UltraChart ctr)
{
    ctr.SuspendLayout();
    
    // [set some properties in the axes, chart text, labels, etc...]
    
    ctr.LineChart.DrawStyle = this.DrawStyle;
    ctr.LineChart.EndStyle = this.EndStyle;
    ctr.LineChart.HighLightLines = this.HighLightLines;
    ctr.LineChart.StartStyle = this.StartStyle;
    ctr.LineChart.Thickness = this.Thickness;

    ctr.Invalidate();
    ctr.ResumeLayout(false);
    ctr.PerformLayout();
}

I am calling this after I make changes in a property grid.

The strangest part (or not) is that, if I change the draw style or the start/end style, I can see the changes in the chart, but the same does not happen when I change the line thickness or the HighlightLines properties.

Hello,

This should really work. I tried it in my sample, pasted the method and called it in the 'Click' event of the 'UltraButton' control. You could also try it in my sample and see if it works for you. Another thing that could help in this situation might be attaching a small sample project of your own reproducing the issue you are experiencing, I will be happy to investigate it for you.

Please do not hesitate to contact us if you need any additional assistance.

Hello,

I am checking about the progress of this issue. Please let me know If you need any further assistance on this.