When did you download DXVK 0.63? It was broken for a couple days on 396.45. Delete the folder ~/.local/share/lutris/runtime/dxvk/0.63 and try relaunching. You can also try using the latest master. Put the master folder in ~/.local/share/lutris/runtime/dxvk, right-click WoW in your Lutris library > Configure > Runner options > and type master in the dxvk text field.