There is a bug in the ancient scrolls 5 Rift Valley City Baron mission.

If every territory wants to become a baron, it needs to complete the small task of "helping the residents of XX". In your game, you joined the imperial army to liberate Rift Valley City, and the position of the Lord of Rift Valley changed hands. The new Lord of Blackthorn may not be able to display this small task because of some display problems. When you help several residents of Rift Valley City, come back and see the Lord's reaction. That should be enough.