Why aren't ShopPay Installments working on my new store?

Hi Guys,

I have recently launched a new store as usual but when I started selling, I have realized that no orders were placed using ShopPay Installments as a payment method. This was very suspicious because on previous stores, about 25% of my orders were placed using installments. I have checked all the connections and settings multiple times and after 100 orders, there was still no order placed using installments.

I decided to run a test order and got a technical error message while checkout. Please see the screenshot in google docs:

https://docs.google.com/document/d/1nXzmtQAFDUopw0I-FFrjy6b-T51ZNBsfBGCqWjy26jg/edit?usp=sharing

Does anyone know how to solve this issue?

Any help would be highly appreciated because I am missing out on a ton of revenue.