small minefield bug

[Q]

Sorry it took so long but here is the savegame with the bug I mentioned:
If you open the gamefile you are in the Centaurus system and in charge of the Ukra-Tal empire. You see a marked minefield with several Ukra-Tal ships on it. Move one or all away from the minefield and back again on it. Nothing will happen, no explosion, no clearing of the minefield.
I have idea what may cause this but I am far from being certain. The Rage have a minefield there and they were in conflict with the Ukra-Tal some time ago but now they have a treaty. So may be that the marked minefield dates from the time of the conflict? Anyway I consider this a bug.