I noticed a problem after updating to Unity 5.1: Our app has several AR scenes using the latest Vuforia SDK and an overview scene without AR stuff.
When I enter an AR scene all uGUI related elements are not rendered. They are active. I can push a button and the action is executed. On the other hand the non-AR scenes show all UI elements as before.
It is strange that this behaviour only occurs when running on the iOS device but not in editor mode.
As everything worked fine in previous releases I wonder if there were any relevant changes in 5.1?
Update: I just installed 5.0.1 and can confirm that the same code works as expected under iOS. I am using Xcode 6.2 and will try an update.