I added a form based off a model in a macro partial view. It renders and fires fine but the values are all null in the surfacecontroller. Why is this? The code is copied from a partial view and the error only occurs while used in a macro. I'm in 7.1.8.

@inherits Umbraco.Web.Macros.PartialViewMacroPage
@{
    var nl = new NewsletterModel();
}

@using (Ajax.BeginForm("NewsletterSignup", "Newsletter", new AjaxOptions
{
    ...
}))
{
    @Html.AntiForgeryToken()

    @Html.LabelFor(model => nl.Email)
    @Html.TextBoxFor(model => nl.Email)
    <input type="submit" />
}