The Rain Festival Beetle despawned

The Rain Festival Beetle strongbox spawned right before the entrance to the Viper Napuatzi fight. When the beetle walked through the entrance, it completely disappeared. Should not be allowed to wander into boss areas if it will despawn.

Where it spawned:
https://imgur.com/a/7rPTc6R

Where it disappeared:
https://imgur.com/a/VqPl5yi