How can I make my scene brighter in Linear color space with GearVR in single-pass stereo?

I have issues with my app's colors in Linear color space. The colors are different and the whole scene is darker. I am in single-pass stereo since mutli-pass doesn't work with GearVR. I am currently using Unity 2018.1.1f1 and the Samsung S8. When I change the color space to Gamma, the colors are properly rendered but I prefer staying in Linear. I tried converting from Linear to Gamma by script but it did not change anything. Here are my rendering settings:

I also tried in Unity 2018.1.4f1, 2018.1.5f1, 2018.1.6f1 and 2018.2.0b11
What can I do to solve my issue?
Thank you!