I am unable to cancel a scouting assignment when I assign a scout to an individual on the individual players report screen. For instance, If I assign my scout to a player to scout indefinitely on the players reports screen and I would instead prefer to scout that player for a week when I select cancel assignment the player still has a scout assigned to him. You can still cancel the assignment in the scouting section under scout priorities, but this is less convenient than using the players report screen.