I seem to run into a bug that prevents my creep from moving onto a specific walkable tile. Even when I give a manual move() command to move onto the rampart on its bottom right, it still will not work. See this screenshot:

The creep is not fatigued and there is nothing else occupying the tile as you can see. It's not a pathfinder issue, because as I said even a manual move() will not work. This is room E29N19 but I've seen it in others too.