Diacritical marks are truncated via Active Record

Yes, the problem still exists. In the meantime, I created a hack, that updates the field that might contain a diacritical mark , by using the driver class, like this:

$conn = new mysqli($hostname, $username, $password, $database);
$sql = "UPDATE mytable SET myfield='$myfield' WHERE key = '$key'";

That runs after the insert that looks like this

$this->db->insert('mytable',$values);

But yes, this is still a problem.