Problems with RTC_GEOMETRY_TYPE_FLAT_LINEAR_CURVE (3.5.0)

I am having some very odd issues with RTC_GEOMETRY_TYPE_FLAT_LINEAR_CURVE.

I am intersecting  rays with a mixture of lines and triangle geometry.

embree 3.5.0 is returning the correct line primitive in the ID of the ray hit for the line p0->p1

 I then compute the intersection location on the line in two ways as a sanity check

• using p0+(p1-p0)*ray.u
• using ray.org+ray.dir*ray.tnear ( should be close within radius of line)

Both computed locations are on very close to the line from p0->p1, but on many occasions they are significantly different. It appears ray.u is in error.

The radius of the line is much smaller than the problematic errors.