From Knux of Australia:

The Big Breakfast, a morning cartoon show in Oz has been canned. As a result, the repeat showing of Sonic Underground has been cut short. The show was part of a reshowing of the most popular cartoon shows voted for. This probably means Sonic Underground including the rumored "Lost episodes" will never be seen again as after Agro's Cartoon connection was cancelled, there was a 3 year gap before a show like it came out. Channel 7 has declined to explain why the show has been axed.