Steps to reproduce:
1. Download repro.zip and open ExampleScene
2. Make sure that single pass is on and oculus is connected.
3. Play game, particles shader works
4. Open GlobalFog.cs uncomment line 41 ( [ImageEffectOpaque] )
5. Play game, distortion shader isn't rendering

Expected results:
Distortion shader should work with and with out [ImageEffectOpaque]
Actual results:
Distortion Shader works when [ImageEffectOpaque] is commented.

Reproduced with:
5.4.1f1
5.4.2f2
5.5.0b11