Corrupted boss despawned after killing map boss from modifier

Hello,

I am not sure what happened is intended or a bug:

After I killed Rathbreaker (the hyena boss) in a corrupted nexus, 1) a bunch of hyena demons and hyena centaurs spawned as usual and 2) the corrupted boss also spawned. I managed to clear the adds but died before killing the corrupted boss. At this point, I see the corrupted boss waiting and the resurrect button. I click on it ... and as I respawn I see the "map completed" notification. The corrupted boss had been despawned. The loots were gone and I could not summon Doryani. And the map was not taken into account for the cleansing nexus quest. However, all uncompleted corrupted maps in the area were properly cleansed.

I understand there is a system to prevent exploiting a boss fight, but it should either be disabled once the boss is dead or not despawn corrupted bosses. Unless I misunderstood something and we only have one attempt at killing a corrupted boss?