To reproduce:
1. Open up the attached project
2. Open "scene" it contains an animated cube. (with movememnt and scale animated)
3. Enter play mode to see the animation
4. Now, select the cube in scene, open up it's animator and select the transition between the move and scale states
5. Note that the preview should appear in the inspector (sometimes it doesn't, then you have to select the cube and the transition again)
6. Press play on the preview, notice that the scale animation is not shown in the preview, only the movement

Regression since 4.3.4f1
It seems that only the scale curves are like this, as adding a rotation to the animation actually showed up in the preview