Bug Report - Mission X

I couldn't find a proper bug reporting function anywhere so I thought I'd post this here.  On mission X when I upgrade my metal refinery, may apply to the power plant but haven't tested, I get a notice that I failed the "Do not let any buildings get destroyed objective.  The only other possibility is if the flying swarm units are attacking my towers directly but I haven't seen any in-game prompts notifying me that the enemies can do that.