Case law is full of examples where supervisors, managers, and leaders were told of harassment or other illegal behaviors, but did nothing. In 100% of cases, this results in bad news for the organization, and for the leader involved.
Bad behavior happens. The courts understand this. But they are a lot less understanding when organizations fail to take action.
Taking action on these things is not always pleasant. We get that. It's awkward, it's time-consuming, it's unfamiliar.