You’ll want to confirm the context of how were those orders received, to identify whether there is a problem. I say this because receiving an order with the status of Pending Payment
is not necessarily a sign of something being broken.
This is the status that orders are set to while the plugin waits for the customer to complete payment. Sometimes, if the customer leaves the checkout process before completing it, the order will remain in that status.
You’ll want to test the checkout process yourself. Try placing an order as a customer would, and confirm whether it goes through correctly. If the issue is still happening, note what do you see on the front-end, as a customer. Are any errors given, for example?
Additionally, can you confirm to us which exactly is the plugin you are using for your payment gateway?