Atahualpa
Chieftain
No, this is real, it's unexcusable, ununderstandable, illogical and totally stupid.
I took this russian city a few turns ago. The russians counter-attacked, leaving only one artillery. I gave it up, withdrew and decided to return another day. The city is now empty for several turns and the AI has not taken it back. Maybe it will do so when it gets out of rebellion, I don't know, there is hardly a reason not to take it back immediately.
Take a look:

Wonder what the AI is thinking. I've added the save game and an auto save from the previous turn.
I took this russian city a few turns ago. The russians counter-attacked, leaving only one artillery. I gave it up, withdrew and decided to return another day. The city is now empty for several turns and the AI has not taken it back. Maybe it will do so when it gets out of rebellion, I don't know, there is hardly a reason not to take it back immediately.
Take a look:

Wonder what the AI is thinking. I've added the save game and an auto save from the previous turn.