Hi,
I am sure this must be something silly. I don't see why scaling different GO would not work, are they separated and not part of the same hierarchy? It could be conflicting with another part of your project.
Have you try to isolate the problem? empty scene, and try to scale two GO first, then more.
Could you share your scale by action, maybe something in here can be spotted. I tried with 3 set scale on 3 GO and it works fine on 1.2
Bye,
Jean