I have enabled the advanced ui on a number of dropdowns and a multi-select on this page http://www.eandhbaxendale.com/online-enquiries/easi-joist-enquiry/ the enhanced ui works perfect until you hit next and something fails validation then it gets stripped from them all. It doesn't appear to be a plugin or theme specific incompatibility because on my local test version which is exhibiting the same behaviour I have disabled all the plugins except gravity forms and have tried switching to the default twenty ten and twenty eleven themes and they also have the same problem. http://i.imgur.com/JLCnN.png
Edit: This bug is only present when ajax is enabled.