that would be WHOIS, however, it will not show "private" or "secret" channel you are not also in
(exception: it might show you all channels if you are an ircop, depends on the ircd and your operator settings)
that doesn't show any channels where user is in. Just list the user info. Username has n rather than i. So that should list the channels. Any idea why this is the case?
Perhaps the ircd protects the users' privacy by only making channel information available to ircops.
This means that technically the ircd is not rfc-compliant since numeric 319 should list channels the user is on in response to WHOIS (except private and secret channels)
Maybe you should read about the ircd being used.