OAuth2 implicit grant (token flow) does not work in IE/.Net Winform WebBrowser

I'm unable to reproduce this on Windows 10. I created a new Windows Forms app, added a web browser control to it, and wrote the following code. I saw a message for loading (among others), the redirect_receiver page, complete with an access token. Perhaps you can try this stripped-down version of the code and see if it works for you?

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        this.webBrowser1.DocumentCompleted += WebBrowser1_DocumentCompleted;
        this.webBrowser1.Navigate("https://www.dropbox.com/1/oauth2/authorize?response_type=token&client_id=0pr10otpma2qtln&redirect_uri=https://www.dropbox.com/1/oauth2/redirect_receiver");
    }

    private void WebBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) {
        MessageBox.Show("document completed: " + e.Url.AbsoluteUri);
    }
}