Crescent Sweep is a cost effective ultimate and it has its drawbacks. It usually doesn't miss unless the target is doing a movement type ability like charging down a line would always miss, that's normal. The striking radius is shorter than the animation, targets moving backwards within the last 1/5th of the animation also don't get hit half the time, that's also normal.
Lately though I been seeing Crescent Sweep missing on targets that are just standing still within melee range in front of me, not doing any special attacks or maneuvers. I also see it no longer hits multiple targets while stealthed instead only dealing its crit damage to the first one struck then severely reduced, if any, damage to the remainder targets. If it now has a chance to miss standing targets, that would be nice to have included that in the patch notes as well.