Arcane Assauklt now bugged?

[Lythe Vodaine]

Before the last patch I always started fights with Arcane Assault from my two wizards. After the patch however, whenever I try to use Arcane Assault, the sound plays, but the wizards only stutter on spot while their grimoire opens and closes again; no projectile appears though. Any hint on how I can get rid of this? Arcane Assault is the only per encounter attack of my low-level wizards, and I have to rely on it, unless I want to rest after every encounter...

 

EDIT:

Apparently, it's only bugged when cast while sneaking.

Edited June 4, 2015 by Lythe Vodaine

[Qbert]

Last night i had unlimited arcane assaults, as long as i clicked the button before or maybe right as soon as the previous one hit.  Aloth spammed it at animats at least 10 times in a row.  I'll have to see if i can replicate it this evening before counting it as an official bug.