After beating an AI earlier today I was going to destroy the rest of their stuff just for kicks and giggles. I decided instead to exit as the Victory voice just kept repeating that I had won the game over and over and over.
It was me as Advent Loayalist versus and Advent Rebel. They surrendered after I destroyed their titan. The only victory condition on was Last Capital Standing (planet version not ship). I however, never destoryed their capital planet. I wonder if that has something to do with it.