Hello, I was getting mad, because all instances of a grenade were affected when only one of them set visibility off.
I think it is because this has been deprecated.
According to Unity manual:
Removed in version 5.3.0p1
Property renderer has been deprecated. Use GetComponent<Renderer>() instead. (UnityUpgradable)
It used to work flawlessly, but since Unity update, it doesn't. I have tried getting a component / set property of type renderer as manual suggests, but still the same behaviour, the renderer is turned off for all instances of that object.