This is happening almost all the time. Bonfire, showcased in the video, is just one of the many cases i met while playing with Shurikens. I bet there are other skills, that have same problems with horizontal collision.
In video, as you can see, shuriken projectiles do not pass through plane terrain and do not hit nearby monsters. In such situations monsters can be hit only if you come into close combat range.
Sorry about audio, i didn’t think, that radio will be also recorded 
