Oops. You're correct. The WWF set is even in the International 2002 pages. I'll go through the Scott Monthly updates and see if it appears there. I should have received the 2020 Volume 6, but it hasn't arrived yet.
I looked through the Scott Monthly Updates from August 2016 to September 2020. I didn't find the stamp. However, I am missing the July 2017 update, which does contain Zaire.
I'm sure the civil war has caused much disruption in everything relating to the country, just like the civil war in Liberia did. Scott is adding the stamps from Liberia issued during the civil war there to the catalog. There are bits and pieces of stamps from Zaire during the early 2000s that Scott is starting to add now as well. Despite the change in name to Congo Democratic Republic (CDR), Scott is continuing to list new issues under Zaire.
Gibbons lists the CDR stamps under that name, but the listings in my 2008 catalog do not go to 2002.
It may show up eventually in the catalogs. My Scott volume 6 is the 2017 edition, but as I said, I am waiting for the 2020 to arrive. I don't know if the stamp was listed between 2018 and now.
Thanks for all the help. I also just found this in Stampworld. They show the mini-sheet being issued in 2003. My 2017 Scott's catalog stops at 2002 for Zaire.
Michael,
I have the July 2017 update. Under Zaire, it states
"Numerous stamps on a variety of topics having year dates of 2002-2012 and inscription "Republique Democratique du Congo" apparently were not available in the Congo"
Looks like Scott has added more of the older stamps since the 2017 catalog.
Richard, thanks for looking it up. I don't know what I did with that issue. I have all the others. It won't matter after I get the new Volume 6, however.