You should hopefully be able to fix the problem with the next update. You would have to run the auto grid generation function after spawning the tiles.
Edit: Another way to do it that would take some more work is to create a child actor of tile_parent with an additional integer array and edge cost array. The integer array would hold the array indexes on the grid of the surrounding tiles to be modified while the edge cost array would hold the edge costs of the same tiles. The indexes in the array would have to be set automatically depending on the index of the main tile. Then in the event graph of the Grid Manager you would get all actors of your new tile type and set the indexes in their integer arrays to the costs of the corresponding structs in their edge arrays. Significantly more complicated, I know. But that’s one way to do it before the new update hits the marketplace.