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.

UPDATE: APPLY THE EYELASH MAT POSE FIRST, then create the layer above the Base. Transfer the nodes from Base to the upper layer. The apply the full mat pose and/or the head mat pose.

The eyelash mat pose keeps deleting the added layer.