Same problem for me. I am at the end of the "Eliminate Empire" quest but I cannot complete it because Northern Empire has a Total Strength over 1 million (!), which is absurd because Northern Empire doesn't have any land left, and I have eliminated everyone except for two lords with no armies (one is stuck in a glitch in the map, the other is the king but he somehow disappeared from the map). I wish TaleWorlds would solve this issue because it's really frustrating, I am basically stuck with the main quest.