Hi,
If I understand correctly, you are having your contact form mail sent to a gmail address, when you test did you use a non-gmail address sent from the form?
Please try installing the WP Mail Logging plugin, and test again it will capture the error messages.
Then afterward please start a new thread and include a admin login in the private content area so we can take a closer look.
As this is not your thread your login info will not be private in this thread.

Best regards,
Mike

Hi,
I noticed that in the console you have this error:

Failed to set referrer policy: The value '' is not one of 'no-referrer', 'no-referrer-when-downgrade', 'origin', 'origin-when-cross-origin', 'same-origin', 'strict-origin', 'strict-origin-when-cross-origin', or 'unsafe-url'. The referrer policy has been left unchanged.

and I found this solution: Failed to set referrer policy error
that may shed so light on it from within your CDN, cache plugin, or .htaccess file.

Please go into your .htaccess file and find and change the following:
Header set Referrer-Policy “”
to
Header set Referrer-Policy “origin”

or see if this is a option in your CDN

Best regards,
Mike

Hi,
I will ask the team to check on iPhone and post a screenshot, I included the Android screenshot in the Private Content area.

Best regards,
Mike

Hi,
Glad this helped.
The latest version is 4.4.1, try going to your Theme Forest account and downloading the latest version, and manually updating via FTP.
First please make a full backup using your webhost backup tools.
Then via FTP, look for the “enfold” folder at /wp-content/themes/enfold/ and rename to “enfold-old” then upload the new version as the folder “enfold”
Please don’t try to overwrite the theme folder, as this will leave old files behind and cause errors.
Once you have cleared your browser cache and tested that your site is working correctly, you can delete the old folder “enfold-old”.
If for some reason you want to go back to the old version, simply remove the new folder and change the name of “enfold-old” back to “enfold”
There have been many changes since v4.0.7, so you may need to make a few minor adjustments once you update.
If you don’t feel comfortable with these steps, we can assist if you post FTP access in the Private Content area, and link to your copy of Enfold (that you download from your Theme Forest account) in DropBox or Google drive.

Best regards,
Mike

Hi,
You should place it before the last ?> you can move that down a few lines, it is the end of the file.
Your function should look like this:

<?php 

// logo personnalise
function childtheme_custom_login() {
echo '<link rel="stylesheet" type="text/css" href="' . get_bloginfo('stylesheet_directory') . '/login.css" />';
}

add_action('login_head', 'childtheme_custom_login');

function add_google_remarketing(){
?>
<script type="text/javascript">
var districtmPixel = {};
districtmPixel.revenueValue = '0.00';
(function(){
var dm = document.createElement('script');
dm.async = true;
dm.src = '//cdn.pixlads.com/agencies/1/advertisers/1163/audience.js';
var ref = document.getElementsByTagName('script')[0];
ref.parentNode.insertBefore(dm, ref);
})();
</script>
<?php
}
add_action('wp_footer', 'add_google_remarketing');


?>

Please make these changes via FTP or your webhost file manager, so if you make a mistake and your site crashes you can edit the file back to the way it was.
Notice how I placed your code with the