I'm rather sure it happened in game LG3 (n. 3452). After conquering it always said "you conquer and pillage 0 gold pieces", I looked at my gold and I don't think it changed. In other games I have to see yet.
Found the bug and fixed it. It was just a display-bug, so the gold was still taken Anyway, it should now show you correct amount of gold taken from the enemy.