I note that the Eyelash Mat Poses are intended for a so-called "Layer 2" of the eyelashes, in the Material Room. You will need to manually create a Layer above the Base layer, which the Mat Pose is unable to create. The work-around is as follows: Apply the Eyelash Mat Pose you desire (there are 3 to choose from). Now in the Material Room, go to the Eyelash material. Add a Layer by clicking on the plus (+) sign next to the word Base. Copy the shader nodes in the Base lay over to the layer called Layer_1. Apply the Full Mat and/or the Head Mat after this step.

If you don't do these steps in this order, there will be an artifact appearing in the eyeball when the eyes are moved.

Eternal Hobbyist