After completing the achievement Equivalent Exchange and claiming a Golden Shadow Hunter Vol’jin, your hard earned regular copy can no longer be dusted.
The regular copy of Shadow Hunter Vol’jin was the FREE legendary of the set, and thoose cards can never be dusted.
Then why do they let new or returning players craft it when everyone else got it free?
If it can’t ever be dusted then being able to craft it in the first place is also a bug.