Australian Isabella King dominated the women's omnium competition, finishing on only seven points, 11 points ahead of China's Xiaojuan Diao on 18. Ellis was third on 21 points with fellow Kiwi Jaime Nielsen fifth on 25.
Hamilton's Nielsen won the individual pursuit and was second in the 500m time trial.
Olympic sprint medallist Shane Perkins (AUS) edged Matt Archibald and Eddie Dawkins in qualifying for the sprint in 10.155s in a chilly Adelaide Super-Drome and was then unmatched in the elimination series, accounting for compatriot Peter Lewis in two straight rides in the final.
Archibald (Invercargill) was the best of the Kiwis, accounting for China's Wang Shengwei and Australians Jacob Schmid and Mitchell Bullen before he was beaten by Lewis 2-0 in the semifinal and to Nathan Hart in the ride-off for bronze.
Dawkins (Invercargill), who won the keirin on the first day, finished fifth when he won the ride-off for the minor placings after losing to Perkins in a closely-fought quarter-final. Ethan Mitchell lost to Lewis, also in the quarter-finals.
Dunedin's Katie Schofield missed out in the repechage for a place in the quarter-finals in the women's sprint.
The five-day competition reverts back to sprints and keirin competition in two sessions today.