Order information not recording in MP

I’ve had a few (rare) issues with orders not being recorded in the database properly. We are using Paypal Chained payments and the payments are being sent properly, and the order created. However, the order information that goes into the wp_postmeta table isn’t being populated. Some of the rows are, but not the really, really, important ones like mp_shipping_info and mp_cart_info – this leaves us without that crucial information. The other rows in that table fill up and relate correctly to the entry in wp_posts

Now, what I’m wondering is when does that information get populated? Before the payment transaction in some sort of pending status, or after the payment transaction? I know our site has been getting out of memory errors and I’m wondering if that happened during the transaction process, and the info didn’t get written after the customer came back from paypal, or if there is some other issue. Some insight would be useful, this is the second its happened to this seller in two months and she’s getting pretty frustrated with me because I don’t have answers for her.