Trying my luck here…
For some reason $ionicActionSheet no longer works on iOS 8.4 in an existing app, while it works as expected on iOS 9.
The problem is that $ionicActionSheet.show will show only a backdrop. If you tap on it (anywhere) the backdrop will disappear.
The funny thing is that I am not able to reproduce this on an app made from scratch / minimal app.
Oddly enough, this issue was caused simply when using the minified app css file. The cause is likely within gulp-minify-css/clean-css.
For the time being I’ll stick to using the plain css version until gulp-minify-css updates and tests its dependency on newer clean-css.