Order stuck at domain selection

I'm having a problem similar to the one reported earlier at https://premium.wpmudev.org/forums/topic/greyed-outfreeze-during-order

I'm using Portal theme. Can't get past domain selection if using WHMCS cart style other than "Modern". Tried Verticalsteps, Ajax and Web20cart.

Would really prefer a better looking cart than Modern.

You can verify at http://bizlift.com/account/?whmcsportal%5Bpage%5D=whmcs%3A%2F%2Fbizlift.com%2Fwhmcsaccount%2Fcart.php%3Fa%3Dadd%26pid%3D2