Sarm told me a few nights ago that it seemed to have been fixed. I went to test it on dummies and a heroic dungeon, noticing the following:
1. It can now actually hit targets at 40 yards max range, when aimed properly.
2. Rage inducing misses seem to be fixed.
3. It can now consistently hit multiple targets.
4. Both the cast and each individual impact can now proc Arcane Missiles. Previously, AM only procced on cast.
#4 is particularly significant, because AO was already a pretty strong talent if it actually worked. With this buff, AO becomes one of the strongest talent combinations when paired with Nether Tempest:
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Also, AO is now by far the strongest cleave talent, which are pretty common in Highmaul. Let's see if AO gains some traction in the next few weeks!