They have no free spot on a vert or hor position.
Cross the two 'loopindex("..") = 0' conditions in event 11 to have the diagonals available.
That will also mean that they are taken into account when calculating/choosing the shortest path.
Up to you if you like that or not. The results are very different. I did not like it at all in a example that i made.
Also, it will be slower. In the end, when you dont limit the search tree (and that is ALWAYS true), you end up checking to many possibilitys.
It is not a case of finding the shortest available walkable tile to the click position, that is pretty easy, you can do that on your own.
The case is to find the shortest available walkable tile that can be reached.
So, if you got a clickable tile buried deep down, and you want to check for every walkable tile arround it (dont matter how far away) if it can be reach and if it is the closest reachable, your search tree goes deep and exponential in amount of choices.
But that is up to you eh.
Now it checks just hor and vertical (4 tiles) in a simple loop. Whatever loop you want to choose will work (in exponential longer ticks).