Can't build walls, game bugged

in game when i try to place walls (not the building walls the sort of free walls like you can use to surround your town) it wigs out and does various things like, showing the posts but not the actual wall, not letting me tell the hearthlings to build them, and stopping my interface from working, now i couldnt take a picture before this caused me to crash and corrupted the world but this seems to happen everytime i try to place defensive walls in the game.