If you're experiencing problems displaying elements using the Underlay property of a Revit view, the feature just might be behaving as designed.
We recently had a team working on a high-rise project and they wanted to use the Level 8 plan as an underlay for the Level 5 design. In other words, using a level above as a reference for a lower level.
PROBLEM: The walls didn't show, but plumbing fixtures did. As a matter of fact, it seemed like anything that was supposed to be cut in plan view was not showing. We tried just about everything to fix the problem...changed the view discipline, checked the phase filters, and so on.
It turns out that the View Range settings are crucial to the behavior of underlays. If EITHER the host view or the underlay have the View Depth set so that the views 'cross' each other - cut object styles will not be displayed. This usually happens when View Depth is set to Unlimited.
While this seems to make sense for an upper level that uses a lower level as an underlay, it behaves the same way in the opposite. If the View Depth of the upper level includes the lower level within the view range, Revit thinks the elements are already being displayed and does not show them in the underlay.