This topic is halfway between general ParaView support in in-situ support, as it involves the generation of in-situ scripts using ParaView.
In recent versions or ParaView (at least 5.6 to current master), the ghost cell generator filter is not accessible (grayed out/inactive), using a multiblock (unstructured) dataset, while I seem to remember being able to access it a year or so ago.
Recently, a colleague had some artifacts using “cell data to point data” with Catalyst in a parallel run, while the issue did not appear with the EnSight reader (our Catalyst scripts being generated from EnSight format inputs in most cases).
Simply forcing a “generate ghost cells” in the Catalyst Python script seemed to do the trick and fix the issue, but I am unable to find/remember why the filter cannot be accesses from the ParaView GUI, even when not needed, so as to make it easier to insert in in Catalyst scripts or VTK scripts generated through the ParaView graphical interface (Qt/desktop in our case).
Is there a reason this filter is not accessible by default ? Is inserting it in an in-situ script a bad solution (i.e. are there hidden issues) ? I could try to force things at the Catalyst adaptor level (in C++), but generating ghost cells may be overkill (and costly) for cases where we simply need a few clips, while it seems needed for more complex operations (cell to point, gradients, streamlines, …)