PayPal payments may be pending on their side and in these cases, PayPal provides a reason, albeit a vague one. Pending payments may take PayPal anywhere from an hour to a few days to clear, but Selly will process the order as soon as PayPal completes the payment.
The currency that the payment is being made in isn't supported by the seller's PayPal account. The seller will have to add this currency to their PayPal or change the product's currency to one that their PayPal supports.
PayPal is conducting checks regarding the payment to ensure it's legitimacy. This is almost certainly triggered by either party's account not being verified.
PayPal account has to be verified.
No specified reason.