With the peasants that got stuck - you can transfer that unit into an army on the world map (use Garrison ability to mark that peasant battalion), and transfer it back. We will look into that location, and the problem will be solved late this month with the new pathfinding.
With the Mills - can you confirm if restarting the game doesn`t fix it? If so you can try deleting the mill and placing a new one.
And thanks for your reports!