funny because the invincibility skill should activate since I am the one that is attacking and each time it did not activate and that unit was killed in the second round and it is a lvl 140 aura which means it should last around 4 rounds before it starts taking damage

Did you guys disable the invincibility attribute of the aura Heavy tank on the ww map? I attacked several cities today and in every fight the aura tanks skill did not activate like it should have