Is zos aware of the bug that takes all your ult when you try to dawnbreaker someone but you do no damage and have no animation. I noticed it's more likely to happen if you have an object in front of you such as a pillar. So if I was to dodge roll around los to turn around with a dawnbreaker there's a chance I'll completely waste my ult.
Not sure if this is related as well but I only have seen this specced as a stam character, albeit this might be because it's easier to los equating to you doing it more frequently.