Skirmish Victory Not Unlocking

I spend most of my time at the Skirmish Hall.

However, in half of the games, the AI has been defeated, but the quest does not complete.

I go map hunting after their units/buildings, and I think that I usually have destroyed everything.

I could go on for another hour...

Perhaps there could be some late game thing that removes the fog of war?

Not a satellite, perhaps something religious!