Transactional emails not sent

Since a few weeks I haven’t received my transactional emails anymore and I see nothing in https://app-smtp.sendinblue.com/statistics

I sent a test email and it is fine.

Here is my code :

wp_mail($Email_Address, $Email_Title, $Email_Content, $Headers)

$Email_Address -> [email protected]
$Headers -> array(1) {
[0]=>
string(38) “Content-Type: text/html; charset=UTF-8”
}