Interesting. Would be good to know how it worked out in the end.Yes, very annoying. I’ve had that happen quite a few times. I kept changing browsers and even used a VPN. I can’t recall how I got it to bring up the pre-filled screen, but success eventually.
With my first card application by GT (two years ago) there weren’t any website issues. However, with both of the next two GT applications it seemed to take multiple attempts, over days, before the correct web-page came up. I would leave it for a day or so, and try again. The correct page would appear momentarily, but then change to another page (that needed a SSN). Not real sure what was going on. Perhaps a cookies issue.
Mine wasn’t a GT though as I was applying through a targeted referral link. When trying to use GT, it linked me to an error page.