So, i echo'd the SQL for the courses to the page, the ID for that user is 1823
Looking in the oderoptions table, there is no record for that user:
SELECT * FROM orderoptions WHERE FKUSerID = 1823
Looking at your checkout pages, I see that you have a store order details behavior on the pp_confirm page to save the course to the order options table, but that behavior does not exist on the regular confirm page.
most likely, the people that are reporting the problem are checking out using the Direct checkout method and entering the CC details on your site which goes through the confirm page.
the people not having the problem are using the PayPal express checkout option which goes through the pp_confirm page..
