PHP regex to find last occurrence of date not working as expected

Question

I'm trying to parse an email and find the last occurrence of the pattern XXXX-XX-XX where X is an integer. I then want to insert that into a database, but it's entering 0000-00-00 each time. The other parts (body and from) are successfully parsed.

    // PULL IN EMAIL
    $Parser = new PhpMimeMailParser\Parser();
    $Parser->setStream(fopen("php://stdin", "r"));

    // SET VAIABLES OF 'FROM' AND 'BODY'
    $from_raw = $Parser->getHeader('from');
    $entry_raw = $Parser->getMessageBody('text');

    // GRAB NAME AND EMAIL FROM 'FROM'
    $from = preg_split('/\s*<([^>]*)>/', $from_raw, -1, PREG_SPLIT_NO_EMPTY|PREG_SPLIT_DELIM_CAPTURE);

    $regex = '/.*\b\K\d{4}-\d{2}-\d{2}/s';
    preg_match_all($regex, $entry_raw, $date, PREG_SET_ORDER, 0);

    $date = $date[0][0];

    // TRIM 'BODY' DOWN TO FIRST PARAGRAPH
    $entry = explode("\n", $entry_raw);

    // CONNECT TO DATABASE
    $hostname = "xxx";
    $database = "xxx";
    $username = "xxx";
    $password = "xxx";

    $con = mysqli_connect($hostname, $username, $password, $database) or die (mysql_error());

    if ($con->connect_error) {
        die("ERROR: Unable to connect: " . $con->connect_error);
    }

    $stmt = $con->prepare("SELECT id FROM users WHERE email=?");
    $stmt->bind_param("s", $from[1]);
    $stmt->execute();
    $stmt->bind_result($id);
    $stmt->fetch();
    $stmt->close();

    if ($id) {
        $stmt = $con->prepare("INSERT INTO entries (entry, user_id, date) VALUES (?, ?, ?)");
        $stmt->bind_param("sis", $entry[0], $id, $date);
        $stmt->execute();
        $stmt->close();
    }

I've tried this code in a separate file and it works fine:

    $entry_raw = "this is some text 1111-11-11 2222-22-22 this is some more text";
    $regex = '/.*\b\K\d{4}-\d{2}-\d{2}/s';
    preg_match_all($regex, $entry_raw, $date, PREG_SET_ORDER, 0);
    $date = $date[0][0];
    echo $date;