Hi Luyang,
The following conditions must be true:
* the private data is shared to a public open data group
* "Private Item Views" beta capability is enabled for your site
* You are logged in on your site
* In the search results, on the left hand side under "Views", select "Items"
If you've done all those and the items still don't appear, I'd recommend filing a ticket with support.
This feature is still in beta and is not completely documented. We welcome any and all feedback!
Courtney