Hi people -
Interesting problem I've got here. I'm using Magento 2 and after a considerable battle I've beaten it into submission. I've got the point of testing checkout and setting up Paypal - all good. I click the checkout icon and I see my basket and the items in it fine. I click the Proceed to Checkout button and move on to the form where I fill in my email address and shipping details. That's what I want.
However, if on the first screen I enter a discount code, click the Apply Discount button, wait for the confirmation and then click Proceed to Checkout immediately I get a popup inviting me to sign in or register (to my own site). Doesn't happen if you wait about 5 seconds or so.
If you move slowly, you'll never see it. If you've been through the screens as many times as I have and you just move straight to the button for proceed and click it, this gets in the way.
I can't write on that screen that all users have to count to 10 before they click the button, so I assume there's somewhere I haven't found yet to turn this off. Any help you can give would be appreciated.
It is a bug, I have seen it too.
I reccommend report it on GitHub: https://github.com/magento/magento2/issues