To reproduce the ticket issue:

Please confirm you have signed into ea.com, then click this link to open buy page, you can see the it will open a new blank page, if go back to buy page, and click "Purchase TA Funds", then open lockbox modal, you will see the checkout flow is destroyed.

Now the buy page is prod CCTA Offers, if you want to verify test page, please replace the link url inside above script code `window.open()` with your test page url.