Texture/Shadow Issue with Jin Hair G8M
I'm having an issue with the specified Hair. For reference, here is the hair in question:
https://www.daz3d.com/jin-hair-for-genesis-8-and-81-males
Including examples at the link of what it's supposed to look like.
But when I did an Iray Preview, I got these black edges on the tips:

I played around with as much in the Surfaces tab as I could think of, and when I turned off the Opacity for all of its pieces, I got this instead of the hair being totally invisible:

It also seemed like the direction of these black blobs shifted when I changed the direction of the environmental light in the scene, so I'm wondering if this is an issue with how the hair model is dealing with the shadow effect?
I am on Daz 4.15; I haven't updated because of the Ghost Light issue with the latest versions (4.20+), so if there a way that this issue can be resolved, or is updating my only option?

Comments
I tried using this hair recently, and came across this issue. Turns out, I posted about this two years go and forgot about it, likely because I never got an answer for it. Rather than necroBUMPing that old topic, I'm going to make a new one.
The hair in question is this:
https://www.daz3d.com/jin-hair-for-genesis-8-and-81-males
When I turn in Iray preview with the hair applied to a model, I get these strange shadows around the hair as you can see in the first three attached images. The position of these smudges shift with the direction of the light. When I set the opacity of all of the hair Surfaces to 0%, I get this strange shadow haircap thing with smudges coming out of it, seen in the other four attached images. This phenomenon is not seen in the promo images for the hair in the link above.
For anyone who has experienced an issue like this, have you found a way to resolve this?
If it matters, I'm still on DAZ 4.15, since the newer releases change how Ghostlights work and I still have scenes dependent on the ones I've already set up.
Posting a new thread isn't an improvement on bumping an old one.
Is the figure in the centre of the world (no translations) or further out? Try switching the Instance Optimisation in the Editor tab of Render Settings to something else (and then back again if there are isntacnes in the scene), does that help?
Yes, I haven't moved them at all from the world center. However, in testing, the phenomenon still happens even if I move him off the central grid.
I've played with all the settings under Render Settings > Optimization, including Instance Optimization, but there was no change at all on this phenomenon.
OK, if it is strtill in the centre then it isn't the issue that the Instance Optimisation might help with (which is surfaces getting too close to resolve due to the limits of numeric precision - being away from the centre would have been cause, not cure)