Joined solid geometry cannot be copied as a whole. Instead, select the individual extrusions, etc., using Pick box or Ctrl-select and copy them.
Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 26.1.0.0 (26.1.0.34)
Syntax
C#
public static FailureDefinitionId CannotCopyJoinedGeometryWarn { get; }