[FrankTrollman]

I've run into something similar with found fortresses. I believe that it has to do with the fact that "construct fortress" and "destroy fortress" are the same command. That is, when you want to create a lab or tear an already built lab down, you go to the same place on the command menu.

So if you start building a fortress, and you find a free fortress, your character's orders become "destroy fortress" because they are on build fortress and there's already a fortress there when the command resolves.

-Frank