It seems that when enemies step out from behind a pillar to shoot you, when you retaliate, they are already back behind the obstruction, so you cannot hit them. Meanwhile, if you try the same thing against a sentry turret, your character stands out in the open for long enough to get shot at. Can enemies stay out of concealment long enough to get shot, please?
Actually you can do the same as the enemy: If you do a retaliate and an enemy shoots the character that is in retaliate out from a full cover your character will shoot him. There is a bug that sometimes f. up the rendering and visually the enemy is already back in cover but the retaliate still hits him.