As I recall from one of your previous posts, your data comes from a DG simulation. I don’t know the details of how Ghost Cells Generator works, but I suspect that once again the discontinuous nature of your data is interfering with finding correct matches.
The first thing to try is to run Clean to Grid first and then Ghost Cells Generator. The generator might not be checking for duplicate points on each process.
I expect Ghost Cells Generator will use global ids if you have them. I would expect global ids on discontinuous boundaries would mess up the ghost cell generation. If you have them, you can try deleting them. You might be able to use the Pass Arrays filter to do that.