Reproduction steps:
1. Open the attached project "UIAdditiveTest.zip";
2. Build the standalone project;
3. Open the built version;
4. Observe the shield icon in the window;
5. Press ALT+TAB to minimize the window;
6. Observe the shield icon has disappeared in the window.

Expected results: gameObjects will be shown as usual;
Actual results: gameObject with the specific shader is not shown after minimizing the build.

Reproduced on: 5.5.3p3, 5.6.1p1, 2017.1.0b9, 2017.2.0a3.

Does not reproduce with DX11.

Not reproducible anymore on 2017.2.1p4.