Template is not refreshing on object property change (Ember 2)

I'm running into an issue with Ember where when I change a property of an object (in this case filteredHeroes) and then set the computed property to be the updated version, my template does not update. How can I force the template to update with the change to the object when the action is called?

In my template, I have:

In my controller I have an action:

calculateStats() {
        var heroes = this.get("filteredHeroes");

        var valueOfAttackSpeedPerCP = 5.5;
        var valueOfPowerPerCP = 6;

        var attackSpeed = this.get('cpAttackSpeed') * valueOfAttackSpeedPerCP;
        var power = this.get('cpPower') * valueOfPowerPerCP;

        for (var i = 0; i < heroes.length; i++) {
            //Set Attacks per second for the specific hero
            heroes[i]._data.AttacksPerSecond = (1 / (heroes[i]._data.attributesByLevel[14]['BaseAttackTime'] / ((heroes[i]._data.attributesByLevel[14]['AttackSpeedRating'] + attackSpeed) / 100)));   
        }
        this.set('filteredHeroes', heroes);
    }

Thanks for any help!