Using eZ Find you can not find hidden objects in admin interface.

In the site.ini.append.php of eZ Find is the following line:

SearchViewHandling=template

Setting //*SearchViewHandling// to //default*// we will be able to find for hidden objects in the backend.

The other way of making it work is using //*SearchViewHandling=template// and create an override of the //extension/ezfind/design/admin2/templates/content/search.tpl// template, adding the //ignore_visibility*// parameter to the fetch. Example:

{set search=fetch(content,search,
                      hash(text,$search_text,
                           section_id,$search_section_id,
                           subtree_array,$search_subtree_array,
                           sort_by,array('modified',false()),
                           offset,$view_parameters.offset,
                           ignore_visibility,true(),
                           limit,$page_limit))}

This only seems to be affecting eZ Find's search, and not the standard search engine.
If we disable ezfind and then update the search index running //*php bin/php/updatesearchindex.php --clean// and setting //SearchViewHandling=template// we are still able to find hidden objects in the backend, even if we aren't using the //ignore_visibility*// parameter in our fetch on the template (design/admin2/templates/content/search.tpl).

Steps to reproduce

1. Log into the administration backend;
2. Create an object;
3. Set it to hidden;
4. Update solr search index;
5. Search for your hidden object.