This is my usual method (Daz to Blender), and I’ve never had a problem with any hair until this particular prop. I’ve been wrangling with this for 2 days, so hopefully some fresh eyes can figure this out.
You need to increase the render depth for transparency:
This hair style has more transparent planes stacked behind each other than the render depth for transparency is set to. Therefore Cycles can not see “through” all of them, the overlapping areas turn opaque and black. Go quite high with the transparency depth in this case - about 25 or so.