Hello LordSith, thank you for posting.
Normally, the Fog Cloak allows you to shoot at targets affected by Acid Fog.
However, if your character herself is affected by the Acid Fog, I don't think that she should be able to shoot at all.
That's because the Fog Cloak does not allow you to avoid movement penalties from being in a Solid Fog or Acid Fog. So I think that the arrow would not be able to fly away.
Whereas, an arrow shot from outside the fog could reach its target because the arrow is flying fast enough.
Now, if your character was not affected by Acid Fog, then that's a bug. I will have a look, just in case. Cheers