Was running a ult focused build last match, and it seemed to trigger at random upon the ultimate being ended, but much more often if it ended automatically vs manual canceled. I also had effects that raised the duration of the ultimate, so maybe its not updating the animation state when the timer runs out properly. Like looping around to being a really high timer on the client side of "this player is in ultimate, display ult model until timer depleted], or breaking the value [though it does seem to end if a lot of time passes without dying or ulting again].