Anybody know how to fix these guys?

https://preview.redd.it/bkirwdnm0goe1.png?width=1630&format=png&auto=webp&s=3411b3ae467bac7bc5eba6fe6c03e46a9bd00b1f

Theres families who are stuck on the bank with planks and they can't find their way across to where theyre supposed to be building. I've reassigned them and assigned them to different things and they still stay stuck on the bank...