I´m running Lightroom 6.7 latest update on an iMac 27" with MacOs Sierra latest update and Apple Magic Mouse.
In Develop module catching and moving a point in RGB curve don´t work properly anymore. At release 6.4 it worked well.
When catching a point in a curve I can´t move it constantly. It feels like a magnetic force will keep the point where it is. For example when trying to move a point up I move the mouse curser, but the point keeps where it is unless I reach the end of the histogra. Then it jumps to the border and gets sticky there.
This behaviour only appears when developing my RAW files after some adjustments. When opening a brand new RAW file, it works. But after some minutes it don´t work anymore.
I am not a Mac user, but previous posts suggest this is a Sierra problem with LR 6.7.
See some of the other "sierra" posts.
I have same problem. Not only that but also as soon as press the mouse the cross hair disappears and you have no idea where you are pulling the curve to. The problem seems to be more persistent towards the edges of the curve then the mid section.