So we have been getting a few complaints each day from customers who cannot complete checkout. The clients with issues cannot get past Step 1 of the checkout. They say they click the Continue button but either the loading animation doesn't stop, or it does stop but doesn't move to the next step. Different browsers or computers does not make a difference, it seems to be happening on certain internet connections.
I had OneStepCheckout enabled when we first started getting complaints, and I switched to Magento's One Page Checkout hoping that that would fix it. It did not. So with OneStepCheckout, their order would not go through (they filled out all their info and then clicked the Place Order button). With Magento's default checkout, they cannot get past the first step. So it seems like something is not allowing the buttons to be clicked, or the information is not sending after the button is clicked. There is no error message, they just can't continue the checkout.
It seems to be only international customers (99% Brazil but I think there was a complaint from Sweden too), but maybe USA customers just aren't emailing us about it.
I cannot replicate this issue. If I log in with these customers accounts, I can complete the checkout just fine.
If these customers use a different internet connection (at a friend's house or on a 3g phone for example) that usually fixes their problem.
This has been happening since early/mid June :(