Can Sombra hack Bastion out of his ult?
Bastion will stay in his ultimate tank mode until the timer on that runs out or he's killed (or some other character's ability is used that can bring him out of tank mode). It doesn't matter if Sombra uses her hack ability or her ultimate. I tested this with a friend in a custom match after seeing a PotG of Bastion ulting, followed by an enemy Sombra ulting to try and shut him down. It didn't go so well for the Sombra.