Voronoi mesh boolean problem

Working with voronoi cells in various forms. When the original form is a surface, the attached script works fine. However, when I try to do the same thing with meshes, I get some strange results. Any insight on why the boolean difference is giving leaving only some of the cells? Image and file attached.
Thank you,

GHscript_meshBoolQuestion.gh (51.8 KB)
mesh_bool_issue.3dm (261.1 KB)