Just tried this mission myself. as with all the others the colonists are invisible.
Yes, that sounds like the bug.
Originally Posted by ceefax742
...But in addition I can not kill the drones. They just stand there stunned for about 30 seconds and then they reactivate with full health and shields. Even an exploit when they have almost no health left only leaves them stunned. The only ones that die are the Proto Drones, and at one point I was fighting almost 20 of them, while trying to find the active points.
That sounds like it's working as planned. The idea is that Borg Drones that do not die are actually protected by Borg Nodes. What you want to do, is find the Nodes first, destroy them and only then try and kill the Borg Drones. Proto Drones, if I'm not mistaken are Drones that are spawned by a Tactical Drone, which means they're not protected by a Node therefore they can be easily killed.