Checkout fields validation doesn’t work after update

After updating Woocommerce to 3.2.6 this code below stopped working. Before it was working fine. Can you please advice? Is the name of hook checkout process changed? I tried to output something at the beginning and I think it never reached my function.
Also I’m using child theme, could that cause the problem? Once again this was working fine before updating!
Thanks!!!

add_action('woocommerce_checkout_process', 'wp_delivery_date_validation');

function wp_delivery_date_validation() {
	date_default_timezone_set('America/Los_Angeles');
    $shipping_date = filter_input(INPUT_POST, 'shipping_date');
    $shipping_time = filter_input(INPUT_POST, 'shipping_time');
	$st = "";
	preg_match("/^(\d{1,2}):00 ([AP])M$/", $shipping_time, $st);
	$time = $st[2]=='P'?(int)$st[1]+12:(int)$st[1];
	$date = date('Y-m-d',strtotime($shipping_date));
	if (($date == date('Y-m-d', strtotime(date('Y-m-d',time()) . "+1 day")) && $time < 12) ||
		$date < date('Y-m-d', strtotime(date('Y-m-d',time()) . "+1 day"))) {
		wc_add_notice(__('<strong>Delivery Date</strong> must be at least 1 day in advance.'), 'error');
	}
}