If you use HubSpot’s non-HubSpot forms tracking, you may see completed checkouts recorded in HubSpot but nothing from the guest-details step of a two-step checkout. This is expected HubSpot behavior.
Why this happens. HubSpot’s collected forms feature only records native form submissions made with a standard submit button, and it ignores hidden fields. In a two-step checkout, the guest-details step (where your guest enters their name, email, and phone and clicks Continue) saves data in the background rather than submitting a form, so HubSpot’s tracker never sees it. The final payment step is a real form submit, which is why completed checkouts do appear in HubSpot.