You have posted an explosive starship :)
As soon as we approach it, Braooooum !)
Maybe the cupolla was made with TnT?
Seems the best is kill this Cupolla, and remake another one with another method :)

No it's not the cuppola, if you Copy / drag out and make an boolean operation with another new volume that works!
It's the Starship the problem :)
Seems boolean operation Union of it composant are not clean!