Does not work captchas inside of webforms

Hi,
using Webform 6.x-3.19; image captcha refresh is enabled, but nothing shown.
a sample form looks like this: hope it helps.
Probably just some form_alter form identification issue?

<form action="/en/support/contact/feedback.html" accept-charset="UTF-8" method="post"
id="webform-client-form-324" class="webform-client-form" enctype="multipart/form-data">
<div>
    <div class="webform-component webform-component-textarea" id="webform-component-message">
        <div class="form-item" id="edit-submitted-message-wrapper">
            <div class="resizable-textarea">
                <span>
                    <textarea cols="60" rows="5" name="submitted[message]" id="edit-submitted-message"
                        class="form-textarea resizable required textarea-processed">Type here to send us your message</textarea><div
                            class="grippie" style="margin-right: -6px;">
                        </div>
                </span>
            </div>
        </div>
    </div>
    <div class="webform-component webform-component-textfield" id="webform-component-your-name">
        <div class="form-item" id="edit-submitted-your-name-wrapper">
            <input type="text" maxlength="70" name="submitted[your_name]" id="edit-submitted-your-name"
                size="60" value="" class="form-text required" data-cip-id="edit-submitted-your-name">
            <div class="description">
                <p>
                    Please, enter your name, so we know who you are.</p>
            </div>
        </div>
    </div>
    <div class="webform-component webform-component-email" id="webform-component-your-email">
        <div class="form-item" id="edit-submitted-your-email-wrapper">
            <input class="form-text form-email required email" type="email" id="edit-submitted-your-email"
                name="submitted[your_email]" size="60" data-cip-id="edit-submitted-your-email">
            <div class="description">
                <p>
                    Please, enter your email, so we can contact you.</p>
            </div>
        </div>
    </div>
    <div class="webform-component webform-component-markup" id="webform-component-salutation">
        <br>
        <br>
        Thank you.
        <br>
        <br>
        &nbsp;</div>
    <input type="hidden" name="details[sid]" id="edit-details-sid" value="">
    <input type="hidden" name="details[page_num]" id="edit-details-page-num" value="1">
    <input type="hidden" name="details[page_count]" id="edit-details-page-count" value="1">
    <input type="hidden" name="details[finished]" id="edit-details-finished" value="0">
    <input type="hidden" name="form_build_id" id="form-93dc4ea65a2e78219eff0e1434d46e77"
        value="form-93dc4ea65a2e78219eff0e1434d46e77">
    <input type="hidden" name="form_id" id="edit-webform-client-form-324" value="webform_client_form_324">
    <div id="edit-actions" class="form-actions form-wrapper">
        <div class="captcha">
            <input type="hidden" name="captcha_sid" id="edit-captcha-sid" value="3528">
            <input type="hidden" name="captcha_token" id="edit-captcha-token" value="18a4e550cbcadc0ca44a25e6636456f9">
            <img src="/en/image_captcha/3528/1377589957" class="captcha_image" id="captcha_image_3528"
                alt="Image CAPTCHA" title="Image CAPTCHA"><div class="form-item" id="edit-captcha-response-wrapper">
                    <label for="edit-captcha-response">
                        What code is in the image?: <span class="form-required" title="This field is required.">
                            *</span></label>
                    <input type="text" maxlength="128" name="captcha_response" id="edit-captcha-response"
                        size="15" value="" class="form-text required" autocomplete="off" data-cip-id="edit-captcha-response">
                    <div class="description">
                        Enter the characters shown in the image.</div>
                </div>
        </div>
        <input type="submit" name="op" id="edit-submit" value="Submit" class="form-submit">
    </div>
</div>
</form>

btw: thanks for the wonderful functionality!