Repeatable bug, the Preservation Mission cannot be completed: After clearing the initial area, the rest of the mission is practically empty. If you walk around enough, you can find an escort mission where you have to follow some apparatus, collect "knowledge" or Resonant Runes I guess, and move the apparatus to a location. Once it gets to its location, the world is empty again until you find what looks like a boss room with multiple levels; there are groups of mobs within but no boss spawns after you clear the entire thing out. Appears to be no way to complete the mission (or the correlating quest).