In AGOL / Portal sections of Gallery / Groups / Content I´m able to filter content by "assigned to ..." statement. But I´m not able to find items which aren´t assigned to any Category / Group / ...
(We decided to assign each item to at minimum one Category, Group, ... to be able to filter data easily. But unfortunately we are not able to find items which were "forgotten" without assignment.)
=> Please, add the "not in any Category", "not in any Group" statements to Gallery / Groups / Content filters of AGOL / Portal.