When you see that page, it usually means that something about your booking has changed. Go to MMB - if you accept the changes it goes back to the standard UG page.

Good timing - this JUST happened to me too. Sure enough, after I've accepted the 5 min change to one of the flight times, the normal upgrade page was displayed.

QR has innovated once again! This communication approach is 5 star all the way. Traditional, boring airlines would email you about the schedule change. QR communicates this by showing you a different interface when you go to upgrade. It's all aligned with the GOING PLACES slogan - as you navigate the website, you are going to a different place.