Error when making credit card payment using Square extension (Opencart 3)

When making a credit card payment in Opencart 3 using the Square extension, the payment goes through (I can see it in Square), but the order does not appear to go through on the Opencart side of things.



The screenshot above (credit card info removed) was a successful payment, but an error message comes up and the page does not continue. Unfortunately, it's an empty error telling me nothing.

If I go to Sales > Orders in Opencart, the order is not there unless I filter for missing orders.

Does anyone have any idea what might be happening or how I can bug test this further?

Thanks in advance!