The URL is only accessible if the user is in the correct org from which policy was created
If the policy is created under a sub-org and then the delegated action will be only accessible from that sub-org.
By default, when a user logins to its tenant, he is in TLOU org and that's why he is not unable to access this link and its returning 404 error.
User needs to switch to the organization under which the policy is created in order to access this page as we have a check in place