His 3 targets are baymax, merlin and jack sparrow, his white skill takes time to come through enough that his shuriken pops starts its animation, also during this time for the shuriken pops animation but before the white skill hits Merlin he has turned Baymax invisible making him untargetable. So by the time in the gif the shuriken pops are to be released no targets are there. That is how i think this bug occurred.
Again just a guess.