Groups invite feature can't see shared contact list?

I am trying to use the Invite Friends (ie: add members) feature of the Groups page:

https://accounts.zoho.com/u/h#groups/allgroups

with a particular group selected. I select the Invite Friends button. I'm attempting to use the Choose from Contacts feature, which shows the My Contacts dialog.

Unfortunately, this only finds contact listings actually directly owned by the account that's logged in, in category All Contacts in the My Contacts column on the Contacts page).

I need it to find Shared Contacts, because I need to delegate member management to group moderators, who will therefore need to share contacts.

For this test I am logged in as the user who owns the group that owns the shared contacts. So there shouldn't be any permissions problem.

Am I doing something wrong?

- Graham