Playing as the Altarians, building the Doomsday generator.
I got invaded on said planet. Obviously this improvement was demolised for the invading race (the all conquering humans).
The very next turn I took back my PQ26 planet (the very nerve)
But I couldn`t rebuild my Doomsday generator.
Now I am slightly miffed. I have put up with your politeness for too long ,
prepare too feel my wrath from the wraith MK II.
I don`t know if this is a bug for all race specific buildings that have been demolished during invasion.