How to reproduce:
1. Open user-submitted project (IssueProject)
2. Open scene '1'
3. Enter Play Mode
4. Click outside of Unity editor to lose focus
5. Refocus on Unity editor

Expected result: the cube remains colored green
Actual result: the cube resets to color black

Reproducible with: 2018.3.1f1, 2019.1.0a12
Could not test with: 2018.2.20f1, 2018.3.0a11, (The shader has dependencies to a LWRP version, incompatible with these versions)

Notes:
The shader in the project is dependant on LWRP
The issue only reproduces when the version control setting under Project Settings > Editor is set to 'Hidden Meta Files'