I'm having trouble understanding when the Assault ability "Flush" works and when it doesn't. From the XCOM wikia page:
Fire a shot that causes enemies to run out of cover. The shot is easy to hit with, but does reduced damage.
That page goes on to say that Flush adds +30 to Aim, halves the damage, and that even on a miss it can force a target to move. But I've tried it several times, and the Muton at the business end hasn't budged.
Are there certain enemies this doesn't work against? Are they protected from moving if they're in full cover, or they have cover from two directions?