Today, I received a save file where the computer's units disappear from the map (either flee or are defeated), and along with them, a neutral group of peasants also vanishes!
Please note that the hero has no magic skills at all!
Very interesting! It turns out that the computer defeats the neutrals but loses its entire army! I thought that was impossible. But from a theoretical point of view, this situation falls under the definition of a defeat, although the computer shouldn't be defeated: if the neutrals are defeated, the hero should still have at least one unit remaining. This needs further investigation.