Buffer Visualization - Custom Depth not working

I am looking forward to implement an outline PostProcessMaterial similarly to the Editor selection highlight. There are a number of resources documenting how this can be achieved using the “Custom Depth” feature.
I have been dropped off with a 4.8.3 project which I am extending. To start things off, I have enabled “Render Custom Depth” on some StaticMeshActors and then switched the “View Mode” to “Buffer Visualization” > “Custom Depth”. To my surprise, none of my nodes were visible (see image below).

However, when I setup a blank 4.8.3 project and try the same, it works as expected. Is there something like a global setting, that would disable the “Custom Depth” pass? Is there anything else, I might be missing?

EDIT:
I have just migrated all Asset files in the Content directory into a new project. In this one everything works fine. I guess my problem is kind of solved now. I would still really like to know, what exactly caused the issue. It must have to do with the project settings.

No one? Friendly bump.

In Project Settings, go to the Rendering section, under Post Processing change the Custom Depth-Stencil Pass to “Enable with Stencil”.