To reproduce:
1. Create a new project
2. Build for standalone
3. Open built project
4. Try to select Graphics device to use

Expected result: able to select Graphics device to use
Actual result: the drop-down is greyed out, unable to select Graphics device to use

Reproduced on:
2018.2.0a3 2018.2.12.f1 2018.3.0b6 2019.1.0a5

Not reproduced on:
2017.4.13f1 2018.1.9f2 2018.2.0a1

Notes:
Can't open the build on 2018.2.0a2
Tested with Auto Graphics API for Mac, Metal, OpenGLCore
There is no option to select Graphics device to use on Win 10 machine