I have a zen cart store which has seen over 4,000 orders. We switched from OS Commerce for several reasons, but one was missing orders due to customers not clicking the button to return from PayPal consistently. While zen cart has some issues like that, in the 4k orders we've had since the switch, only three have never made it through to the zen cart admin after being charged in PayPal successfuly. All three were over $1k. The other 3,997 came through with no trouble. I find it hard to believe that only the three largest orders we've had in over a year and a half were the ones who forgot to click a return to PayPal button or closed their browser window before the return or whatever.

I think it must be some kind of bug. Anyone know the back end well enough to throw out some ideas as to what in the works might cause a $1k or greater order to stick?

(I've installed the stuck order push module and when they happen I can push them through now, but we don't want to have to watch so closely on the clients best customers)