Happens all the time on Calico. Seems to be caused by abilities that stop you from doing something/stun you when Calico performs her leap forward ability. Notable culprits in my experience that I can clearly recall: Haze's dagger, Abrams' shoulder charge, Paradox's freeze shot. It happened at other times, too, but I couldn't pinpoint the ability that caused it in the mess of a team fight.
