If you leave the game, when you restart the game and reload your game, you can see on the map a bridge you have built but the villagers will not take the bridge and ignore it as is it does not exist.

So if you need the bridge, like on volcano map where it is mandadory if you build on the west part, you have to delete your bridge then rebuild it on every game session.

This is very weird that in your code, your code will reload a saved bridge and build it on the map but your code decide the bridge does not exist for villagers pathfinding, this is really badly writen code, and a complete nonsense. Not right for a "released game".