I'd consider this a bug; feel free to disagree.
Location: The final "arena" on the right side of Legion of Almire (where you get the key to return to the "main" area), where the spawns are two kats and two almirian knights, and then a gate comes down and you're supposed to go up where turrets, kats, wings, and 4 more almirian knights spawn.
Bug description: When the gate in the middle of the room comes down (when you've killed the 2 almirian knights and the 2 kats at the start), you can "wake" the almirian crusader knights without starting the rest of the event by throwing vials at them or otherwise hitting them without crossing the middle of the room. Then, the "completed" sound jingle plays... before you've started the event.
In my opinion this room is broken. It shouldn't play the jingle if the whole "let's wake the knights without crossing the middle" mechanic was intended. In my opinion the whole event should begin when the gate comes down. Alternatively, the whole event should begin when someone wakes an almirian knight.
This would greatly increase the difficulty of the room which should be a lot of fun - and which is kinda the point of "danger" missions.
I think it was intended, since they patched other tricks right away (like blocking spawners in the other room with statues)
You could just run through the gate if you want to make it more difficult. Or go with randoms as one person almost always does this or does a brandish charge attack next to the edge which pushes them over.