The Tessellated material in pack was not designed to be used with the Landscape Actor since the Landscape Actor requires a very specific material setup to function properly and using tessellated materials on Landscape Actors has many know issues.
That being said i have developed a tessellated material specifically for use with the Landscape Actor which allows for a 3 texture set blend but it is not yet perfected and still has some issues - I may release material later on the marketplace in another pack but until it’s perfected i won’t release it publicly.
The Tessellated material included in pack was designed to be used on tessellated meshes for smaller areas that don’t require exact player collision since the player collision will be derived from the mesh itself, not the tessellated surface
The thread i have linked below demonstrates what the material was designed for, every structural object in scene including the floor uses the Tessellated material to give it more detail and depth
https://forums.unrealengine.com/showthread.php?8552-Abandoned-Tunnel-Scene-WIP&highlight=tunnel
Also if you scroll down in that thread you will see some video clips showcasing some of the different features of the Tessellated Material.