This is clear enough from the rules on defeating attacks:
MELE wrote:Only those strikes that are assigned need be defeated for the creature's marshalling points to be received by the defender.
If strikes ceased to be assigned as soon as they were resolved, then it would never be necessary to roll body checks to defeat attacks, since only strikes that are assigned need to be defeated in order to receive MPs when the attack resolves. I think we can all agree that this is not the case.An attack by a hazard creature is defeated if it is not a detainment attack and all of its strikes directed against (i.e., assigned to) a company are defeated.
Strikes remain assigned until the attack has been completely resolved.