Not sure how that's called, but the radio button to sample the image in"HSL/Color/B&W", doesn't work with the new version, it turns into a magnifying glass and zooms into the image instead of isolation the color I'm trying to affect.
Please do Help > System Info and report the exact version of LR.
Lightroom version: CC 2015.10.1 [ 1117303 ]
Update to CC 2015.12, the latest version, which fixes this problem: Keeping Lightroom Up-to-Date
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