I'm testing some guest scenarios (CWA) in my lab using ISE1.3 and WLC2504 (7.6.130).
I have noticed that redirection to ISE portal doesn't work for apple devices (iOS 7 and later).All other devices like laptops,androids etc work fine.
Seems that the workaround on WLC that bypasses the CNA on iDevices doesn't work in my case.The device tries to open the ISE portal and shows just a blank page (attached photo)
The problem doesn't appear for devices with iOS 6 but only for newer versions.
I've also tried with version 8.0 on WLC without success.