Using the Tree Creator Leaves shaders cause billboards to be drawn with what appears to be incorrect alpha. This only occurs when using MSAA.

How to reproduce
1) Open the attached project and run in player or editor and observe the billboarded trees.
2) Turn MSAA off on the camera or disable anti-aliasing in quality settings.
3) Rerun the project and notice that the trees are now drawn correctly.

A related issue occurs when using the Fast variant of this shader. To do so:
4) Re-enable MSAA.
5) Locate the leaf materials in Environment>Terrain>Trees>Materials>Branch2/7/8.
6) Change the branch shaders to 'Tree Creator Leaves Fast'
7) Locate the tree prefabs in Environment>Terrain>Trees>Models>BananaTree/PalmTreeE/Tree7
8) Open each model's prefab in the Tree Creator and click the Recompute button to generate textures and geometry.
9) Rerun the project and notice that the trees are drawn incorrectly.
10) Disable MSAA and and see the correct billboards.

Reproducible in 2018.3.0b1, 2018.2.6f1, 2018.2.0b9, 2018.2.0b5, 2018.2.0a6, 2018.2.0a2
Not Reproducible in 2018.1.0b13, 2018.1.9f1, 2018.2.0a1