Why is the whole family showing when cut in section? / Sections do not cut through families?

This post is regarding one particular query, you can see the full list by clicking here.

In Revit, some Family Categories are "cuttable" and others are not.

If you wish your family to be shown in section when cut by a section line, or cut plane of a floor plan, the Family Category must be of the "cuttable" variety.

This page gives a list of what Family Categories are cuttable and what are not.

To change the Category of a Family you must open the Family file. In the Properties Portion of the Home Tab in the Ribbon, look for the icon with the little yellow folder in the lower right-hand corner. Pressing this will bring up a dialogue allowing you to choose the Family Category.

It is important to choose a Family Category that is generally in accordance with what the Family in question actually is, because a Family's Category is what dictates how it is drawn in views graphically.