I have gone through the quick start guide. Created a Preview App. Loaded demo article to the Publish Site. Published Collection, Article, Card and Layout. I can't get anything to preview. My Preview App just shows a blank white screen after a loading circle.
We are having the same/similar issue. Eventually, we reinstalled the app and everything came back but before that, some of our (ios) devices were saying "no internet connection" (we confirmed there was a connection) while others just gave us a blank screen (I'd attach a screen shot but it would be a light gray rectangle.)
It appears to have been set off when we added one of our collections to the default phone home collection yesterday afternoon (between 2-5 CST).
FYI, it brought down both iphones and ipads including - IPad2, IPad3, Ipad Mini, Iphone 5, and Iphone 4 running IOS 7, 8, and 9. We haven't started using Android yet, sadly.
Any information would be greatly appreciated. thanks so much!