I installed Woocommerce on my website, tested it in the sandbox, everything seemed fine, now the website has gone live, and half of the payments made with paypal don't go through. Buyers get a "already paid" message and they can't proceed with the order.
What's happening? It's quite urgent, unfortunately, since the site is live and orders are already piling up. And contacting each buyer afterwards to send them a paypal invoice doesn't seem very professional.
I have a business paypal account.