Color Grading: Some Curves don't affect color shifts made using Linear Trackballs

I'm trying to figure out why does it seem like most of the grading curves take effect before the Linear trackballs, which causes it to affect the original image but not the resulting image after the trackballs have taken effect. This is not an issue when using Log trackballs.

Here are screenshots of a test using a simple gradient. Only YRBG and Hue VS Hue curves work, nothing else does!

Bonus Question: Why does Unity Documentation recommend Log for HDR and Linear for LDR when Linear seems to give more control over the resulting image? Example: http://imgur.com/a/VSqNn