Level 6 rally flag problem

Only beasts will respond to rally all flag. I've tried using control groups, dropping minions on flags, using all possible flags, slapping them silly (out of frustration), everything I could think of. I've finished the game and am running through a second time to get the achievements. It didn't do this the first time through, but as I go to replay the level without restarting campaign progress I'm experiencing this issue. Might try resetting campaign progress if worst comes to worst.