From http://www.tigase.org/content/server-does-not-send-invitiation-when-user-granted-membership-members-only-room :

How to replicate:

• User A creates an account

• User B creates an account

• User A logins

• User B logins

• User A binds resource

• User B binds resource

• User A enters a room room@fqdn

• User A configure the room as "member only"

• User A adds user B as "member" using h**p://jabber.org/protocol/muc#admin

• User B receives no invitation

Server SHOULD send an invitation, as per:

XEP-0045 9.5 Modifying the Member List

Regards,

Luca.

(From XEP-0045)

In addition, the service SHOULD send an invitation to any user who has been added to the member list of a members-only room if the user is not currently affiliated with the room.