Steps To Reproduce:

1. Open the attached project.
2. Select the "New Avatar Mask" in the project window.
3. Select humanoid in the inspector and select the left hand to activate it.
4. Hit play in timeline

Observed Result: The hand up animation doesn't play, instead the normal running animation plays.

Actual Result: The hand up animation should play.

Reproducible On: 2018.3.0a5, 2018.2.0b3
Not Reproducible On: 2018.2.0b2

Environment
Occurs On Windows and Mac