Extract Surface does not remove internal surfaces
I have a file [tried with VTU and Fides] written in parallel [MPI]. When I open it I can see internal surfaces on the borders between the parallel partitions of the mesh. The Extract Surface filter has two options, "Piece Invariant" and "Remove Ghost Interfaces" which from their description more or less sound like they should get rid of the internal surfaces but they actually don't [nor does any combination of the two].
Is this a bug? Or am I misunderstanding what these options do?