MiB quickly became infamous for its (mis)management of the con, with gaffes such as a very late-opening dealer room, no lanyards for attendees, and a rather pitiful "party" to celebrate the 10th anniversary of The Transformers: The Movie.
Needless to say, Men in Black was not brought back to participate in BotCon 1997. However, MiB did go on to organize the unofficial TransCon '97 in Chicago, Illinois, at which Onyx Primal was again offered to attendees, due to the fact that they had a significant number of unsold Onyx Primal toys left over from BotCon '96.
TransCon III, which was held in Toledo, Ohio in September 1998, was the MiB's final Transformers-related convention. It shared billing with MicroCon, a MicroMan/Micronauts convention, and MegoCon, which celebrated the Mego dolls from the 1970's and 1980's. The dealer room was largely empty, and the MicroMan & Mego portions of the show were little more than nice displays of personal collections. Still clinging to unsold pieces from the previous two MiB shows, there were more Onyx Primal toys for sale.
TransCon III was so named, according to MiB staff, because it was their third Transformers convention. This would retroactively rename BotCon 1996 as TransCon I. At least in their view.