In SW 2017, a feature was introduced which I call the "closed sketch highlight," meaning when you get a sketch closed and extrude-able, the area inside the boundary changes color to indicate that that loop is closed.
Now, at times, this is fairly handy. however, I've run into situations where that highlight acts as a barrier to clicking on the face or features behind it.
I'm getting to the point where I'm not sure I care if I have this feature at all. However, I can't find where to deactivate it.