On the previous turn, the tile pointed at by the arrow contained 3 wolves. When I hit the turn button, the animation showed them falling over like they had been killed, but after the animation ended the tile still showed 3 wolves. When I moved my army to attack, there were no wolves there. I loaded the autosave (from which I took the screenshot) and it showed that the tile was empty.

Loading the previous autosave shows the wolves in a completely different tile. (I have the autosave frequency set to every turn).
Here's the autosave.
Here's the previous autosave.
Here's the debug.err after loading the previous autosave file.