If you have Cargo Docks, but do not have Ships yet, the pathing system still takes Cargo Docks into account (Cargo Docks reduces embark/disembark movement cost), which prevents you from moving because you can't actually enter the water, even though you've been pathed through the water. (You can still move by choosing a route that doesn't path through the cargo docks.)



this is especially confusing when moving long distances since the unit and the cargo docks can be off screen, but the unit won't move.



(so, in other words, the pathing system should ignore cargo docks when you don't have ships.)