I seem to be unable to retreat from Invasions.  I have had this in several games now.  It seems that when I invade after a battle I am unable to retreat.  My troops will keep fighiting to the death even if I move my ships out of orbit.

1.During a game Invade an enemy planet with ground forces.

2.After first battle click the retreat button to cancel invasion (there must be survivors on both sides for this to happen so attack a planet with a large garrison and large invasion force)

3.Observe that the invasion icon is still present above the planet

4.End Turn

5.Observe that invasion continues even though last turn you chose to retreat

6.If survivors are still present on both sides move fleet out of system

7.End Turn

8.Observe that invasion still continues until all forces on one side are dead

This is a high priority bug as it is not conforming to game design (unless I am missing something).  Players should be able to call off an invasion (maybe taking some losses in the process but still should be able to retreat.

This could cause frustration as the attacking player would require more time to rebuild his army or the defeding player would be unable to stop the attack possibly losing his system.