The hardcore achievement Trophy Hunting has a rare Savage Rockworm required, known areas of the normal ones are located in Act 2; Sirocco Caverns 1. The rare Savage Rockworm can not be found in game, reports are that it has never ever appeared in game. I personally have never seen it, even though I have specifically tried to do so. My only conclusion is that it is bugged. Multiple people have posted about it.
Why hasn't this been addressed at all?