Having been to the Shadow Dragon lair just yesterday, I haven't had a single issue regarding Concealment of either (Greater) Shadow Fiends, Shadow asps or even Ebon Tigers. Either I was missing because of a low Roll or was straight up hitting, with maybe one of two instances of missing due to Concealment over the course of the whole cave. Unless Voidsense enables to completly bypass the Concealment checks, since I have that up at all time...
I'll try to blast some more Shadows and other usually Concealed baddies to see if I meet the same problem as you guys. Will keep you updated on that.