I found it selsewhere that Joe Ruby and Ken Spears worked on the new shows until the former's death. Actually, their animation studio ceased to exist in either 1995 or 1996. Therefore, it makes sense if they both retired shortly afterwards.
My friend Chad Edwards is asking this for a while:
Why PPGZ never aired in North America, Pan-European countries (except French and Italian-speaking territories, Spain, Portugal, Andorra, Greece and Cyprus), the Middle Eastern and African countries (except French and Portuguese-speaking territories)?