Campaign bug - multiple stacks ship travelling

It was really weird.

But somehow I managed to end up with 2 stacks on a ship in a campaign.

A full stack of 10 units in 1, and a 2nd stack of 1 unit in the other.

While the ship stack of 10 could move at full ship speed of 4.0.  the stack of 1 land unit could only move at his regular speed of 2.0, and had to be moved after the ship stack moved 1 spot.

So I would have to manually move the ship one

then move the other stack into the ship again, and keep repeating it.