Blendhsape material issue


i’m having a weird issue. When i export an animation from maya to unreal everything looks good.
But if i scroll the animation, play the scene in game mode ore change the blendshape manually from the moprh target tab, the material will change with a grey color and the part with correctives shapes applied (in that case the eyes) will change in black.

Do you know what happen and how i can fix this?