I was with a newbie group, only third attempt. The group barely managed to pop the last orb of the second set of orbs, but strangely, by doing so, the black orb kinda floated in the middle of the map not doing anything. When it came time for the third set of orbs to pop they never did. Ultima didn't even do its knockback that usually signals when they're coming.
Just something I thought the dev team would like to know.