forms don’t display

I have the below form in a widget area, and it’s not showing up. Regular html shows up fine. I have confirmed that the amp-form element is included in the head of the AMP page.

<form method="post"
    action-xhr="https://app.getresponse.com/add_subscriber.html"    target="_top">
		<p style="font-weight:bold;">Get new blog posts & special alerts!</p>
    <fieldset>
      <label>
        <span>Email:</span>
        <input type="email"
          name="email"
          required>
      </label>
	<input type="hidden" name="campaign_token" value="xxxxx">
	<input type="hidden" name="custom_origin" value="AMP_footer">
	<input type="hidden" name="start_day" value="0">
      <input type="submit"
        value="Join">
    </fieldset>
    <div submit-success>
      <template type="amp-mustache">
        You are now signed up!
      </template>
    </div>
    <div submit-error>
      <template type="amp-mustache">
        Subscription failed
      </template>
    </div>
  </form>