Hair shading model causing green specular response with high melanin values

The hair shading model provides an incorrect spec response when the melanin value used by the hair color node is >= 0.8.

In an otherwise empty material, using the hair shading model creates an overly green spec highlight, as outlined in the screenshots.
The same material using the default lit shading model renders as expected. Both material instances return the same value when using pixel inspector
on the base color buffer.

Is this a known issue? If so - is there a planned fix or suggested workaround?