FrameLoadEnd not firing on page load?

Question

C++ / C#

The trick is that when the page loads, you need to execute the method.

Why doesn't it work in this case?

Doesn't work with FrameLoadEnd :(

bool GoToPrintCard = false;

            if(CanPrint && angle.QuerySelector("#b-case-header > ul.b-case-overview.g-ec > li.case-print > a") != null)
            {
                browser.ExecuteScriptAsync("document.querySelector('#b-case-header > ul.b-case-overview.g-ec > li.case-print > a').click();");
                GoToPrintCard = true;
            }

            if(GoToPrintCard)
            {
                await Task.Run(async delegate
                {
                    while (true)
                    {
                        if (angle.QuerySelector("#print > div.b-print-container > div.b-card-modes > a") != null)
                        {
                            await browser.PrintToPdfAsync(@"C:\Program Files (x86)\ArbitrPdfFiles\1");

                            break;
                        }
                    }
                });
            }

        private async void button3_Click(object sender, EventArgs e)
        {
            await CreatePdf();
        }