Here is a list of potential reasons why a purchase order status might still be on "pending":
1) The transaction has been submitted to the credit card issuer for authorization and is currently awaiting a response from them.
2) The card issuer has declined the payment without providing any specific reasons for the rejection.
3) An internal error suggests that our connection to the payment server is currently unavailable or not functioning.
4) Transaction failed - unable to find payment for the order.
5) Technical issues (such as scheduled maintenance of the payment gateway or a technical error on the payment gateway's end) have led to the inability to receive IPN related to the order.
6) PayPal e-check: In cases of insufficient funds, PayPal will generate an e-check. Typically, e-check clearance by PayPal takes around 5 days.