Delwyn bugged or not?

I often come across this guy (sometimes on new areas so I've not done the wisp already) and there's no wisp at all. The music starts playing but it is not there. Is this a bug or is it only a random chance to appear or something?

No idea but it seems 9 out 10 times I see him no wisps appear either these days.

This definitely happens when all the rares are dead already. Meaning the wisp has vanished and he remains there watching the empty space where the wisp used to be. I’ve definitely observed this pattern many times but it’s always because I killed the rares before finding him.

Oh, I wonder if it might be this? I'll have to be more observant next time. I think if that's the case it obviously happens a lot, they should spawn a new one off-screen somewhere perhaps.