Steps to repro:

1. Open attached project and 'TestScene';
2. Select 'Main Camera' gameobject;
3. Drag camera's X transform position in the Inspector;
4. Observe the tree prefabs on terrain in the Game view.

Expected result:
SpeedTrees don't change their scale while zooming in/out.

Actual result:
SpeedTrees change their scale when zooming in/out (see attached video).
Regression introduced in 2018.1.0a4.

Notes:
- Reproducible in 2018.2.0a1, 2018.1.0b2, 2018.1.0a4;
- Not reproducible in 2018.1.0a3, 2017.3.0p2, 2017.2.1p2;
- Reproducible for both painted and dragged tree prefabs;
- Reproducible in both Editor and Standalone player;
- Reproducible on both Windows and Mac.
- Seemingly reproducible only with these assets (legacy file versions? corrupted assets?)
- Fixed by re-importing, saving, or changing import settings on the troublesome spm files
- Current asset store version of these assets not afflicted