Image sequence from blender not importing to unity

Characters such as Kirby and Steve despite having a 3D model have 2D textures for the eyes Explaining why they are able to go from a spiral to the regular stretched out oval eyes. I attempted to recreate this for a game by using an image sequence in Blender and inserting keyframes to the dope sheet. However, when importing these to Blender, it imports the image texture but not the animation.

Why is this and how do I solve this problem?