UGUI 5.2 Capture Dirty Texture in iOS

I'm using "Screen Space-Camera" Canvas, and capture it to render texture with `Camera.Render()` by setting `Camera.targetTexture`

However, this works for Android, Editor(OSX/WIN) and some iOS devices
iPhone 6 will capture "dirty" result like a UI atlas texture, or a strange transformed texture. (iPad 2 always gets the right result)

Any solution? I'm using Unity 5.2.4f1