This usually happens if you added new Custom# dimension members, new Accounts or new Entities to HFM. After you retrieved the new meta-data in the CXO-Cockpit by starting a Meta-data extract, you select the new members and you hope that they will also be available to the reports.
The reason that they do not show up is because you did not do a full-data extract, followed by a full OLAP database processing after selecting the new members. Either you did not do a data extract at all, or you only did an incremental upload (certain Scenario / year / period combinations).
Only after a full data-extract (a data-extract using the first Load Set) the dimensions in the CXO-Cockpit are rebuilt. And only after a full processing of the OLAP database (so with the 'Data only' checkbox under the 'Process OLAP db' button unchecked) the new members will be selectable and / or visible in the CXO-Cockpit reports.