How to reproduce:
1. Open Unity, go to the Asset Store Window
2. Download and import the "Unity Anima2D" package
3. Open the "UnityChan" Scene
4. Observe as none of the SpriteMeshes appear in the Scene

Expected result: The SpriteMeshes appear in the Scene and Game Views
Actual result: The SpriteMeshes do not appear in the Scene and Game Views

Reproducible with: 2018.2.0a1, 2018.2.0b6
Not reproducible with: 2017.1.0a1, 2017.1.4f1, 2017.2.3p1, 2017.4.4f1, 2018.1.3f1

Notes: Importing the Anima2D package or loading Scenes with SpriteMeshes in them also throws out this error in 2018.2 versions:
Channel missing from vertex stream layout
UnityEngine.Mesh:set_uv(Vector2[])
Anima2D.SpriteMeshInstance:UpdateCurrentMesh() (at Assets/Anima2D/Scripts/SpriteMeshInstance.cs:307)
Anima2D.SpriteMeshInstance:Awake() (at Assets/Anima2D/Scripts/SpriteMeshInstance.cs:274)