exists (u,v) edge with positive capacity and there is not path from $s$ to $u$. and $(u,v)$ is with full capacity in some maximal flow.

Question

Given a network flow and there exists (u,v) edge with positive capacity and there is not path from $s$ to $u$. and $(u,v)$ is with full capacity in some maximal flow.

I've had this questions with true or false and I thought it was false but apparently it is true. Can someone please explain me how this is possible?