In the last game I played, I captured an Anti-starship arachnid fab and build the full cap, but couldn't actually get them to attack anything. They never seem to fire on anything ever. I've tried manually targeting starships, leaving them without orders and free-roaming defender mode, but all to no avail. When manually targeting with them, it doesn't make the sound when something is targeted, so maybe something is stopping them from working.
Not sure if I'm missing something with these, it's been ages since I last used them. Anybody got any ideas?