Error when exporting asset bundle for iOS

Trying to export asset bundle for iOS using 4.6.0b21

There are bunch of messages like this:

Hash for script UnityEngine.EventSystems.BaseRaycaster has not been generated
Hash for script UnityEngine.UI.BaseVertexEffect has not been generated
Hash for script UnityEngine.UI.Graphic has not been generated

and when trying to load the assets on the device i get:

Unhandled Exception: System.Exception: WWW download had an error:The asset bundle...

Error when exporting asset bundle for iOS