Tyrael's Might not working at full hp

I have to use a shout to heal forcibly even if I have max hp, can’t even use a potion. Just make the requirement at 75% hp

I’ve noticed that on my barb sometimes it doesn’t work even at full HP. Usually this is after I take damage and heal back to full w/ Iron Skin, and then I have to use a shout to kick it back in. Weird bug.