Puppeteer Sharp - missing content and blank pages

Question

I have the following code to save html content as a PDF. I am having consistent issues with blank pages and missing content.

using (Browser browser = await Puppeteer.LaunchAsync(launchOptions))
            {
                using (var page = await browser.NewPageAsync())
                {

                    await page.SetContentAsync(pageHTML, new NavigationOptions { WaitUntil = new[] { WaitUntilNavigation.Networkidle0 } });

                    // pull in main css from site for formatting
                    AddTagOptions css = new AddTagOptions() { Url = "https://MYURL.COM/main.css" };
                    await page.AddStyleTagAsync(css);
                    // pull in font-awesome css from site for formatting - linking to our own copy doesn't seem to work
                    AddTagOptions cssFA = new AddTagOptions() { Url = "https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.14.0/css/all.min.css" };
                    await page.AddStyleTagAsync(cssFA);


                    await page.AddStyleTagAsync(new AddTagOptions { Content = inlineCSS });

                    await page.GetContentAsync();

                    await page.WaitForSelectorAsync("#lastelement");

                    var file = await page.PdfDataAsync(pdfOptions);

                    var fileName = "result.pdf";

                    return new FileContentResult(file, "application/pdf")
                    {
                        FileDownloadName = fileName
                    };
                }
            }

Can anyone suggest any tweaks to resolve this problem?

I havce added a network idle check and am waiting for the final element in the supplied HTML (lastelement) but still the same semi-regular blank or incomplete page.