after assigning the "ranged shadow impact" skill point for some reason your shadow missile does not combo anymore. instead fires a single attack, the first one in the normal animation, the attack button becomes unresponsive until the first attack animation finishes, a second or so, and the you can fire again. this makes your normal attack unusable until you respec.

I have the same issue, when you skill the perk that comes after (the one that speed up the firerate of shadow missile) the attacks of shadow missile are normal agaon. Very unfortunate. I hope they'll fix this bug soon. It's pretty annoying.