Here's a newsgroup thread with people talking about Nixx/Zixx in "the old Paw".
https://groups.google.com/d/topic/al...yEw/discussion
I also tried a search and there are no references to "zixx" past 1999:
https://groups.google.com/forum/#!se...erquest$20zixx
He has no Allakhazam or Illia's entry, so he was surely gone in the revamp.