How to reproduce:
1. Open the attached project
2. Open and play test scene
3. Click on the button in the center of the canvas
4. This button calls "Test.OnButtonClicked" that does 2 things:
a. Instantiates prefab called "BigPrefab" located in the "Resources" folder
b. Fires the trigger "Trigger" on the "AnimatedObject"

Actual result: Depending on how fast loading resources on your computer is, this will have 2 outcomes:
- If BigPrefab is loaded faster than the animation "animationTest" is played on the "AnimatedObject", "AnimatedObject" Color.alpha will become 0.
- If BigPrefab is loaded slower than the animation "animationTest" is played, "AnimatedObject" Color.alpha will remain 1.

Expected result: Result of the animation should not depend on how long it takes to load the asset.

Reproducible: 5.4.2f2, 5.5.0b9
Not reproducible: 5.3.6p8

By Design:
When disabling "Write Defaults" in an Animator state, we provide no guarantee that the State is completed during Transition. This is a current limitation of our animation engine. And this means that when disabling WriteDefaults we are dependant on frame rate.

We suggest using WriteDefaults to "on" and fully define the state of the animation when the alpha should be 0.