Issue

ElumTools uses a feature of the Revit API called the Graphics Pipeline Custom Exporter to determine the View Visibility of elements during the calculation commands and to export luminaires.  To use this feature,  Revit requires the Revit Material Libraries be installed and available.

Solution

Reinstall the Revit material libraries according to the procedure described in the Autodesk documentation.  See Autodesk's online help and this blog post for more information.

Error Messages

Could not complete ElumTools command:  CalculateActiveViewCommand

Exception:
Autodesk.Revit.Exceptions.InvalidOperationException: Rendering is currently not supported in the running instance of Revit. One reason for that to happen is that rendering and material libraries are not currently available.
   at Autodesk.Revit.DB.CustomExporter.Export(IList`1 viewIds)
   at ElumTools.CalculateViewExportContext.Calculate(Document doc, IList`1 viewIds, String name, String description)
   at ElumTools.CalculateViewExportContext.Calculate(Document doc, IEnumerable`1 views, Boolean isolate)
   at ElumTools.CalculateActiveViewCommand.ExecuteCalculation()
   at ElumTools.CalculateBaseCommand.Execute()
   at ElumTools.ElumToolsCommand.ExecuteCommand(String& message, ElementSet elements)
   at ElumTools.ElumToolsCommand.ExecuteInternal(String& message, ElementSet elements)
   at ElumTools.ElumToolsCommand.ExecuteTransaction(ExternalCommandData commandData, String& message, ElementSet elements)
   at ElumTools.ElumToolsCommand.Execute(ExternalCommandData commandData, String& message, ElementSet elements)

ElumTools 2016 Release 10 (2016.10.0.1)
RevitAPI
16.0.0.0
16.0.1185.0

C:\Program Files\Autodesk\Revit 2016\RevitAPI.dll

Revit will typically also give you the warning below on startup.