Cookie Shortcode Not Working

The knowledgebase has an example of how to create a shortcode for storing cookie values in form fields.  But I can't get it to work.  I use the Code Snippet plugin and I added a snippet per the Formidable Knowledgebase:

Get a cookie value in a field#

This example creates a shortcode you can use on a page or inside of a form field. Example: [frm_referrer_cookie name="cookie_name_here"] or [frm_referrer_cookie name="frm_url_value"]

add_shortcode( 'frm_referrer_cookie', 'frm_referrer_cookie' );
function frm_referrer_cookie( $atts ) {
	$cookie_name = sanitize_text_field( $atts['name'] );
	$value = '';
	$cookie_name = $cookie_name . COOKIEHASH;
	if ( isset( $_COOKIE[ $cookie_name ] ) ) {
		$value = $_COOKIE[ $cookie_name ];
	}
	return $value;
}

I then have a hidden field with this value in the form:

[frm_referrer_cookie name="referrer"]

I have a cookie plugin for Chrome and can see the cookie 'referrer' is set with a value but when the form is submitted the value of the hidden field is not set.

Any ideas what I'm doing wrong?