How do I generate cash sales using billing operations?

We have a Shopify storefront with orders coming into Netsuite via the (formerly Farapp) connector. Most orders get paid via credit card in Shopify and sync as sales orders in Netsuite. Some orders are on payment terms and need to be invoiced through Netsuite. For the orders that are paid in Shopify upfront, I want those to generate cash sales in the billing operations, and I want the orders on terms to generate invoices. My billing operations for the payments on terms works just fine.

I tried setting up a billing operation schedule to generate the cash sales based on a saved search from a generic payment method (Shopify Payments) with the 'credit card approved' box checked, but only a few end up as cash sales with the majority creating invoices. I've compared sales orders that generated both invoices and cash sales from the same billing operation, but I don't see any noticeable differences. They have the same payment method and no payment terms. I also can't find good documentation on what differentiates the two.