How do I order Rufus to board the fleet during The Norman Conquest tutorial?

A glitch sometimes occurs during the campaign tutorial that makes it impossible to order Rufus to board the fleet when your advisor tells you to do so.

If this occurs, move the fleet back and forth along the small stretch of coastline south of William the Conqueror's location, until it has run out of movement points. You can then end the turn by clicking on the highlighted hourglass icon.

Once the new turn begins, you will be able to order Rufus to board the fleet.