I have noticed that ATC does not work with my C-130 at the point of "tune *** tower" - nothing! All my other sounds work fine in this aircraft except "weapon" (I know I shouldn't use it in this plane :) ) which sounds like an automatic peashooter and keeps firing after trigger release. Weapons work in other aircraft so it seems it's specific to this.
ATC is more of a nuisance though...
John