Why can't I see the sudoer permissions for another user in Ubuntu 18.04?

Question

I am very used to using sudo -l -U <user> to check another user's sudo capabilities but since version 18.04 I can no longer see this. It always comes back blank.

Is there some special setting I need to tweak?

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Update

The user I am executing this with has the following permissions

    (ALL : ALL) ALL
    (ALL : ALL) NOPASSWD: ALL

as shown after executing sudo -l

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Update2

the return code when I execute the command is 1

$ sudo -l -U other_user
$ echo $?
1

Answer 1

The man page for sudo describes the -U option like this:

-U user, --other-user=user

    Used in conjunction with the -l option to list the privileges for user
    instead of for the invoking user. The security policy may restrict
    listing other users' privileges. The sudoers policy only allows root or
    a user with the ALL privilege on the current host to use this option.

This option has not changed since at least Ubuntu 14.04. So, the user who checks this need to have ALL privilege on the system.