Location of Slope's Section Line

When a symbolic line has to overlapped on a model section line, Revit gives us snap to find exact location of the line except below case.

Of course it's not very important. We can just draw a line at nearest location.
But, I just don't like it. WE ARE ENGINEERS!!!

Visibility of Symbolic Line

Everyone may know how useful Symbolic lines are when make families. And visibility setting makes Symbolic line more powerful. With this feature, we can make highly detailed plan or section views without 3D models.

But in some of family templates, the option of 'Show only if Instance is cut' can not be changed.

Visibility setting in a Genetic model template

I just can't understand why this is blocked! (anyone knows?)

And the way I found to change this option is..