After running an Exchange Mailbox Content and Attachments gathering against an Exchange 2010 mailbox server, the reports do not contain any data. If you check the logs for the gathering the following error is logged:
Error: "An unexpected error occurred during the gathering of information store content and attachments. 0x8004010F: MAPI_E_NOT_FOUND" (Mailbox DN)" where Mailbx DN is the mailbox DN for the mailbox you are trying to gather against.
This can occur if your Exchange 2010 servers are a member of a DAG and you run the gathering against the mailbox server that hosts the passive copy of the database which hosts the mailbox(es) you are trying to collect content and attachment data against.
Create a new Exchange Mailbox Content and Attachments gathering targeting the mailbox server that hosts the active copy of the database that hosts the mailbox(es).