Fucking great. Entire backbone of my application logic is to set gameobjects with models to inactive while they are not in use. What a horrible design.

"By design".. unbelievable.
Lost hours trying to figure out what was happening.
No mentions on the docs, no hints, no exception/logs to help.

Terrible way to handle a design flaw.

I just found some code in our code base that also works around this. I ended up here when googling the issue to see if it was fixed. "By design" without any explanation isn't really helpful to people who see this.

Here's the overview of what our code does: after loading a resource and parenting it into the scene, we save off the current activeSelf state of the root object, SetActive(true), look for an Animation component, if found, touch each AnimationState, recursively call this function on each child, and then finally restore the initial activeSelf state. It is not pretty.

I just found some code in our code base that also works around this. I ended up here when googling the issue to see if it was fixed. "By design" without any explanation isn't really helpful to people who see this.

Here's the overview of what our code does: after loading a resource and parenting it into the scene, we save off the current activeSelf state of the root object, SetActive(true), look for an Animation component, if found, touch each AnimationState, recursively call this function on each child, and then finally restore the initial activeSelf state. It is not pretty.

nswers.unity3d.com/questions/785821/gun-reloading-animation-fails-to-find-state.html

There is more to this saga.....

The bug is still there. But I found 2 postings that say something like...
"Click on your animation file in the Unity Project Pane tab, and on the side the Inspector should be there, right click on the Inspector tab and select Debug. Once you're there, simply change the animation type from 2 to 1."

Better solution....

public static void CrossFade(Animator a, string stateName, float dur, int layer, float normalizedTime)
{
if(a && a.enabled && a.gameObject.activeSelf)
{
a.CrossFade(stateName, dur, layer, normalizedTime);
}
}

Also if it is 'by design' then why is there no note in the docs, nor do the doc examples show a if(...) check?

if(animator.enabled)
{
animator.CrossFade( "hunting_crossbow_idle", 0.1f, -1, 0.0f );
}

or

if(gameObject.activeSelf)
{
animator.CrossFade( "hunting_crossbow_idle", 0.1f, -1, 0.0f );
}

On our project we have our own LOD switching (not Unity's LOD built-in)
We hit this bug and it drove us crazy for months.
I now have checking code to only set an animation (CrossFade) if the Animator is enabled.

This is by-design?????????