Hi,
Well we don't have the problem on our end. Are you using the online VAT check or the format check ?
Because we have added some code to handle that for the format check. But for the online check, it's actually handled by the European VIES system for VAT numbers verification. So it's possible that it doesn't like the VAT number if it has some spaes in it. In that case, you could add the line:
$vat = strtoupper(str_replace(array(' ','.'),array('',''),$vat));
before the line:
$result = $client->checkVat(array('countryCode' => substr($vat, 0, 2), 'vatNumber' => substr($vat, 2)));
in the file administrator/components/com_hikashop/helper/vat.php in order to be nice with them.