How to reproduce:
1. Open the attached project named "Case_1229923"
2. Open the "Test" Scene
3. Observe an emissive red Cube in the Scene
4. Open the Test Shadergraph
5. Add a new keyword and save the graph
6. Observe the Cube in the Scene again

Expected result: The cube remains identical
Actual result: The cube becomes solid black

Reproducible with: 2019.3.8f1, 2020.1.0b4, 2020.2.0a5
Could not test with: 2017.4.38f1(No package manager), 2018.4.20f1(Keywords were not yet available)

Reproducible with package versions: 7.1.5, 8.0.1
Not reproducible with package version: 9.0.0(SRP Master Branch as of 2020-03-31)

Notes:
- Keywords became available in SG 7.1.5 (2019.3.0b4)