Hi
One thing that could be throwing things off is that the costs between your nodes is much smaller than the A* algorithm expects. The A* algorithm expects that the cost to reach the goal is at least the euclidean (by default) distance (multiplied by 1000 to make it an integer). In your case, the cost to move between two adjacent nodes (distance 1) is only 100, while the algorithm expects at least 1000.
See Admissible heuristic - Wikipedia
You can either increase it to 1000, or set A* inspector → settings → Heuristic to None.
See also Int3 - A* Pathfinding Project