Having seen the topic here: https://groups.google.com/forum/#!searchin/gwdbeta/preview/gwdbeta/77ir3LjUU1c/EwulieUk6FcJ
I did something similar where I copied the generated preview files over into my Public directory on Dropbox. Again, when I preview the ad (it was created as a rich media ad for DoubleClick) using the Dropbox public link on desktop, the ad performs as expected. However when I use the same link on iPad iOS 7.0 - Chrome or Safari - the first 'page' of the ad loads, but the transition to the rest of the ad never happens.
Could this be an issue with iOS and code that GWD uses to switch pages? Or is it a problem with running the ad from Dropbox? I looked at the iOS Safari console, and I'm not getting any javascript errors. Not really sure where to look for the problem at this point.