I'm stuck in the Draug boss fight (The Eternal Battle). I've seen videos of others beating him and while Aard seemed to have close to no effect (blocked by shield maybe?) I had success with trapping him with Yrden and rolling around him. However, even if I stand directly behind him (so that I can't move any further forward) my sword just swings through the air and doesn't hit the Draug at all. This leads me to believe the game is glitched for me.
Did anyone else experience this? Did I maybe miss something important, eg. using a specific weapon? If not, can I in any way cheat (or, as a last resort, use mods) to skip this boss? I love this game and would hate to abandon it, but I really see no way to progress here.
In case it matters, I play the game on Linux over Steam.