We've isolated the issue. It appears to only manifest if the Default Sharpening value is set to 40. Move the Sharpening Slider to 39 or 41 and the sliders should be active again. We will log a bug for this.
Since updating to LR 2.4 for desktop (on my MacBook Pro running Mojave), it is no longer possible to adjust sliders for additional sharpening settings in the detail panel (e.g. radius and masking) unless the sharpening amount slider is changed from the default setting of 40. I'm assuming this is a bug. I would appreciate if this were fixed asap. Thanks very much.
We've isolated the issue. It appears to only manifest if the Default Sharpening value is set to 40. Move the Sharpening Slider to 39 or 41 and the sliders should be active again. We will log a bug for this.