Can the enemy destroy their own distress beacon in a downed UFO mission?

Solution 1:

Since you were near the end of the game when this happened, it is possible a Sectopod or Gatekeeper accidentally destroyed their own beacon while moving around inside the UFO. This has apparently happened to a few people, according to posts in this thread.

The original post:

Its no wonder the aliens are losing. They allow Gatekeepers inside UFO's. It pretty funny to watch a Gatekeeper move through a UFO. It pretty much trashes everything. My team was suppose to deactivate a distress beacon. Well the Gatekeeper did that portion of the mission for me.

A response:

Sectopods are the best for that. During patrols I've seen them walk into (through) buildings and walls, totally destroying them. Not the best unit in the world for defending a base.

Another user reported a Sectopod doing this in this thread:

Sometimes the aliens will even do it for you. Why they let Sectopods inside I'll never know, but they wreck [things] with every step.