Corrupting Tempest not spawning in map boss arena

I'm playing in a Courtyard map with the Vaal Winds prophecy generating a Corrupting Tempest. The tempest spawns fine in the map, but doesn't at all in the boss arena.
From the arena, I can see a small part of the regular map and the tempest still spawns there while I am in the arena. The same thing happens whether the boss is alive or not.
I am not sure if it is a bug or intended, but it seemed weird to me and wanted to report it.