Liberated civilization remains at war

[Calcifer]

TL;DR: I liberated Kongo, and he remained at war with me for the rest of the game, no matter what I did.

This is the sequence:
1. America takes Kongo capital
2. Kongo remains with only one city, declares war on me, I take their last city so they leave the game.
3. America declares war on me, and I take Mbanza Kongo and liberate it.
4. Kongo appears at war with me, and I cannot trade with him.
5. After roughly 20 turns, Kongo asks for peace, I accept but we are still at war
6. After another 20 turns, Kongo asks another time for peace, I accept but we are still at war
7. I win cultural while Kongo is still at war with me.

Unfortunately I didn't think about kepping the saves, I'm sorry.

Do you know if there is an official way to report bugs?

 

[aito]

The same thing happened to me. I wiped out Geece, then liberated them through a city taken by America. They remain at war with me, even though we made several peace deals.

 

[Andre1986]

I liberated Japan after they had been wiped, but they didn't come back into the game at all.

 

[Calcifer]

I liberated Japan after they had been wiped, but they didn't come back into the game at all.

In my case, kongo showed up on the diplomatic bar only a couple of turns after he was liberated.