I've been going through Voidwatch lately with trusts, trying to nab the KIs as I go, but recently I've found myself completely unable to use /fume to change the enemy's weakness. I was able to before, but can no longer. The ONLY thing that springs to mind is that the last time I used it successfully was fighting Lord Asag where he managed to use Death to kill me, and it didn't work on the subsequent run or ever since.
Is this just some bug, or is there some other thing going on that I might be missing?