How to reproduce:
1. Open Unity
2. Load user submitted project
3. Open 'TestCubeView.unity' scene
4. Notice a grey cube being rendered to Scene view, but a black one in Game view
5. Disable HDR in camera view
6. Notice cube in Game view being rendered correctly (Color is grey like in Scene view)

In addition try to move the cube while playing the scene. Eventually cube will only leave a grey contour in the Game view.
We have contacted the author of the plugin the shader was from and he thinks it is a problem with Depth buffers.

Expected result: Cube is rendered correctly with HDR enabled
Actual result: Cube will not render when HDR is enabled

Reproducible with - 2017.1.0b1, 2017.1.2f1, 2017.2.0a1 2017.2.0f3, 2017.3.0a1, 2017.3.0b7, 2018.1a1
Not reproducible with - 5.6.0a1, 5.6.4p1, 2017.1.0a1, 2017.1.0a6 (Reason: project is not compatible with old Unity versions)