location based opacity masked material shadows

Hello everyone,
I have tried searching for a solution to this for a while but I cannot seem to find it. I have followed the tutorial on location based opacity (A new, community-hosted Unreal Engine Wiki - Announcements and Releases - Unreal Engine Forums) and based on that I have made 2 cube meshes that will cut through selected materials so that I can use them as section boxes. I use these section boxes for creating visualisations of buildings that I have imported from Revit.

The problem is that all the materials no longer cast shadows because I have applied the material function from the location based opacity tutorial to every mesh in the scene.

Does anyone know if it is possible to retain the shadows from the objects after applying masked materials. The shadows disappear when I have build the lighting after applying the materials.