I encountered an issue with Ionic side menus where a previous view would partially obscure the current view. I updated everything, checked all my JS and HTML templates, verified links and state transitions, all to no avail.
I was stuck for quite a while until I finally decided that it’s probably an iOS-specific issue. A search then led me to this Ionic blog entry from 2 months(!) ago: http://blog.ionic.io/ios-9-potential-breaking-change/. I downloaded and applied the patch and that was it.
The issue is caused by an iOS 9 bug that affects AngularJS and thus Ionic. It’s supposedly “isolated to intermittent UI/navigation issues on some apps”. And, of course, I was one of the lucky ones. I can’t believe it hasn’t been fixed yet!