Hello Archon. Sorry for the late reply. As a player, I noticed that sometimes it is as you say. In this case, I stop the skirmish, unequip the guardians and equip them again, by changing a bit the order, but  I always put the headman under the crown. Of course, you can always contact the Support Team if you want an official reply. For me, the Overlords skirmish gave me what it was supposed to give, and this, on the  3 servers I play.