Checkbox not being rendered on form

Hi,

All form fields I am using are working, but when I add a checkbox it does not appear. I saw lots of posts regarding updating the css -webkit-appearance but my problem is the element is not being rendered at all in html. Any ideas?

Rendered HTML:

<p><span class="wpcf7-form-control-wrap mailing"><span class="wpcf7-form-control wpcf7-checkbox"></span></span></p>

My form:

<label> Your Name (required)
    [text* your-name] </label>

[checkbox mailing]

[submit class:button "Send"]

Thank you,
Tristan