I can’t reproduce the error on codepen. It only occurs on my laptop, and only in Chrome, not in Firefox. Looks like it’s caused by some racing conditions. Digged out this old post that appears reporting the same problem,
http://forum.ionicframework.com/t/ion-slide-box-and-ng-repeat/9826
The solution offered there is to add ng-if= to ion-slide-box, that worked for me.
To summarize: ng-repeat inside ion-slide-box may cause trouble. On top of that, if you have a promise to supply data to ng-repeat, ion-slide-box may not be able to update the initial screen and get stucked. Adding ng-if to avoid refreshing DOM before data is ready APPEARS solved the problem.