[Gorgo]

Thanks for all your replies!

To Geoschmo: The game is Gorgos First. Would be appreciated if you could have a look at it!

This is a game where no player uses any intelligence until the next patch (by agreement).

The game is standard 1.41, so no special movement modding is involved.
Some of the ships had a movement of 6/6, some 0/6 (retrofitted and new one, I think).

After I dissolved the fleet, still the ships wouldn't move, even those with the 6/6 movement.

They were frigates and destroyers. I think I had not moved the destroyers before, yet they were properly constructed (6 engines, no warnings).