smooth color transition triangle vertexes

We are SolidWorks Gold Application partner and in our application we create some OGL triangle with a different color on each vertex and usually with previous driver (for example 377.11 ) we can see a smooth color transition.
With The driver (for example 389.08 ) there is no color transition all the triangle are in the same color.
We have used the OpenGl method “glMaterialfv(GL_FRONT_AND_BACK, GL_EMISSION, mat_emission);” but now that no longer works.
I have created a little SolidWorks C++ API sample to reproduce this issue with SolidWorks.

To add detail the color of the triangle with the new drivers seems to be the same on all the triangle but the resulting color seems to be a mix of the 3 vertex color