I’m assuming that you’ve received your VAT registration certificate from HMRC, but your number is showing as invalid on HMRC’s checking website? If so, there does seem to be an issue with new and amended registrations, as detailed here: https://www.gov.uk/government/publications/check-a-uk-vat-number-service-availability-and-issues/check-a-uk-vat-number-service-availability-and-issues
You don’t mention how you’re losing money from this. If you’ve got the certificate, you’re registered – and can issue VAT invoices and reclaim VAT on your costs (subject to the normal rules). It’s possible that some customers may want to check that your registration is valid, as might any foreign based suppliers. If so, until the system is fixed, I’d suggest sending them a copy of your VAT registration certificate together with a screen shot of the page I’ve given the link to. These will prove that your registration is valid and explain why the checker suggests otherwise.