Hi everyone, just a little comment here.
When we did the Tile BP we moved it so the spawn point or socket point would be at the right of the next one, or in the first case at the right of (0,0,0), when you do the GetActorLocation to spawn the NavMesh the socket point of the NMBVC is at the middle of it self, if you only get the actor location half of the nav mesh will be at the previous tile and the other at the new one so here is a solution of how you can get it fixed, a very simple one.
With this you should have no problems with AI trying to get the next Tile because they do have a path to get there.
Hope this works for you.