"Channel: RGB" doesn't appear there on my LR6. Is it somehow hidden?
Forgot to mention you have to be in the point curve mode.
Hi, I somehow dont have the Button in the bottom right corner
Post a screen-clip of your tone curve panel.
Post a screen-clip of the first 10 lines from Lr MENU: Help > System Info.
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Hey was that solved? I have same problem there in no icon in bottom right 😞
The user interface has changed. If you want the Red channel, you click on the red button at the top. If you want all channels at once, you click on the grey channel. You can click on the S-shaped curve icon and see what that does.
Just to clarify, the original question was about Lightroom (Classic) 6, which is an older version and that is what the marked correct" answer therefore refers to. Once switched from "parametric" to "points" mode using that button at lower right, a given colour channel can be selected in a text menu above the Tone Curve working area.
The newly changed interface, e.g. in the latest version 9.3, uses buttons at the top instead: both for selecting a channel, and for switching mode.