C# WebBrowser Body empty - webbrowser-control

Question

.Net Version 4.5.2
When loading a page that returns 302, the browser control does load the redirected URL, presumably correctly. When you examine the call results in Fiddler, the entire correct page is returned from the server.
Now, the page never 'Completes' for a long time, but does go into an 'Interactive' state where you should be able to interact with it, no?
When I look at the WebBrowser's Document, which is not null, it has no content, so you can't access Body, or any element.
The results is encoded - gzip. You have to Decode it in Fiddler to see it.
How do I get the returned HTML to be available in the Document property?
using (browser = new WebBrowser()) {
browser.ClientSize = new Size(800, 600);
browser.ScrollBarsEnabled = false;
browser.ScriptErrorsSuppressed = true;
System.Windows.Forms.HtmlDocument doc = null;
browser.Navigate(_url);
// Wait for control to load page
while (browser.ReadyState != WebBrowserReadyState.Complete)
{
Application.DoEvents();
if (browser.ReadyState == WebBrowserReadyState.Interactive && browser.Document != null)
{
// give some redering time..
Thread.CurrentThread.Join(500);
Application.DoEvents();
doc = browser.Document;
break;
}
}
var elements = browser.Document.GetElementsByTagName("INPUT");
foreach (HtmlElement element in elements)
{
if (element.Name.ToLower().Contains("theInputFieldName"))
{
element.InnerText = NewFieldContentsVariable;
}
//to get the text use : string value = element.GetAttribute("value");
//to set the text use : elemet.InnerText = "something";
}
...