Audio Problem with multiple audio Sources

so, i'm making this kind of audio game, and it has multiple audio sources, among these sources there are some miners with pickaxe. the sound of the pickaxe it's enabled from the pickaxe hit animation.

too bad there's a problem, basically when i pass in front of some miners, their pickaxe it's not heard anymore, same thing if i turn the back to them.

strangely the big auger (which has a continous audio loop) it's heard from everywhere. could it be a sound prority problem? i tried to do some audio priority changing like assigning high priority to one miner and see if i could hear it without problems, but it doesn't seem to change.