i guess this was before Vuoria 2.8? Because now i cannot fiddle with scribts as they are all locked down in some DLL.
Anyways, i am having the same problem, our Background is this:
We want to have several AR Worlds and they are not extremly large but on the other hand, we cannot pump x worlds into one scene.
we use x gameobjects having a custom tracking behavior which just checks: Is my imagemarger beeing found?
If so, load another scene.
To optimize everything i try to keep everything identical throughout the scenes alive including GUI, Gamemangers, AR Camera.
But when i use this keep Alive option, and come in from another scene, alle my imagetarget GameObject containers with custom tracking scripts get disabled an copys of them with empty properties in their components are being initialized. Trouble is, i cannot see why and under what condition or which objcet is responsible for this.
So i guess i cannot use the keep alive behavior. Which is too bad, because we have a gameobject hirarchie underneath this cam and now i need to disassemble it.
Working with vuforia is really often banging your head against a wall, as soon as you try to do something else besides the tutorials.
And please resolve the naming issue with UILabel, UIButton etc. They are in Conflict with NGUI, which is the most sold Unity GUI solution around and supposed to be the base of the next build in GUI solution of unity, as the NGUI Developer was hiered by Unity to do this this way.
I could fix this myself but it was another "Aaaarrghh" in my Vuforia experience.