The mage nobles being missing makes no sense. Even if communications are down, the sky is still red and the news is broadcasting, so they at least know where one calamity is.
Which means they’re either choosing not to something is preventing them from going, neither of which makes sense as they are 3 different clans of nobles in 3 different places.
So the possibility that they would all agree to ignore this or that a single organization could subdue all 3 without anyone noticing is equally crazy.